I'm looking at several different companies for 12 points. Some have door bars with a crossover for the top of the windshield. Some use a roof perimeter bar with A pillar down tubes. Is there any difference in strength? Maybe the down tube design would be easier to weld since you don't have to get between the roof panel and the tubes. But the door bars would be easier to hold in place for tacking and alignment. Dash is coming out also, so I want a cage that will fit close to all of the surfaces.
While I'm on it, there are so many choices for m/s. I've seen EWS .134" wall, DOM .120" wall, DOM .134" wall. I'm planning on a 1 5/8" cage on 2 x 3 frame rails. My old cage was built before they changed the rules for wall thickness, so it won't pass tech.

You can get good welds on top of the cage up by the roof of the car by cutting a hole in the floor and dropping the cage down a little bit, not sure what you are talking about with the crossover bar to the windshield. You want DOM, it doesn't have a seam where it was welded together so it will have better strength/integrity in case of a rollover.

A true full cage will have the cross bar at the
windshield.. on the cages I built I preferred to
run the upper side bars from the main hoop forward
then down the A-pillar.. than when those were in I
put in the front cross bar... if you plan on 8.50
or a 7.50 cert there are other bars that need to be
there... the X in the main rail section and the
diagonal bar in the roof section
EDIT
for the roof weld points I cut holes through the
floor to drop the chassis down and then weld the
tops then lift the chassis up and slide the 6"X6"
plates under the tubes and weld them in.. I left
the plates lose till the end just in case I needed
to drop it again

Halo roof design is not as good or clean. This what you are calling perimeter.

The better is the a-pilar bar to start at main hoop and following the door opening to dash bar. I also prefer a 1.625" dash bar that separates the A-pilar. You can run 1.250" but it can't intersect. When you intersect the A-pilar you can follow the firewall easier without that tough horseshoe bend.

Good point. Sometimes I just don't think. Most of the floor has already been removed.

My old Alston cage had door bars with a cross over. Seemed like the better design to me, too. But what do I know? Planning on welding 2x3 rails to the rocker sills also, for extra strength, and was wanting to use the rails for mounting points for the door bars and main hoop. Would use the frame rails to mount the main hoop diagonals, and run supports straight down from the dash bar to the frame rails also, maybe for mid plate mounts. Didn't know about the diagonal roof bar and floor x-brace for cert. Thanks for the heads up, Mike.

On a unibody car you have to have the bars along
the sills to cert.. I prefer to mount the main hoop
to the side bars instead of the sills... if need be
you over bend the main uprights so they land on the
side bars and still are fairly tight to the side of
the body

On the 2 chassis's shown.. the bottom one has
better front bars.. the top one, the ends out
front are bent too much and would bend easy on
a impact.. start those bend at the upper shock
point and go out to just past the front of the
steering or brake reaction rods.. it makes a
stronger area with less bend

That's what I was planning. Car won't be a modified unibody for long. full length 2x3 frame rails going in. Just haven't decided if I want to stay with a-arm or pull the trigger for struts.

Bang for the buck... struts all the way... and its
a lighter package even more than the fancy tube
K-member ones... for about $1800 you get everything
including brakes.. the only thing you need is the
steering rack(if you go this way make sure you buy
the correct rack.. they make different lengths where
the inner tie rod is and the numbers of turns on the
steering wheel.. its very simple to set up.. way less
work than a A-arm set up

There is no "better", it boils down to what fits the car the best. While some say the roof halo is not as "good", well that depends on the car. Something like a shoebox Chevy, the roof halo is ideal and gives better angles and more strength at the corners.

One thing to keep in mind though............you appear to be looking at "kit" cages. Nobody makes a really good "kit" cage for ANY Mopar. So if you want something that REALLY fits, have a quality shop bend you one up.

.120 wall DOM will pass any sonic test, but DOM will cost you nearly as much as moly.

You're right, Monte. This is for a 70 'Cuda, and I like the way my old door bar design worked. I guess it would be best to have a cage built specific. I would really like the door bars to follow the A pillar to the firewall fairly close.

Never seen an E-body "kit" that fit worth a crap, because most are made to go in front of dash. Have one bent up to fit the car

OK, Monte. Will do. Thanks.

Absolutely agree that GOOD fit only comes from custom bending.

I installed an 8 point kit years ago, the fit was okay, but when it came time to do a 10 point I had a shop here local to me bend up the halo bars but they didn't fit like I have liked so I tweak them to my likings now I'm in the process of adding the snout bars so I'm in the routing stages like was already said no one builds nice cages for e-body's .

I wonder if that's ALL DIY kits. The inside of an E body can't be too much different than an old Camaro/Firebird, and everyone and their brother's make Camaro kits. How do they fit?

Actually used an E body kit( from Jegs) as the hoop fit perfectly in my late B, Nothing else fit of course, but they give you plenty of pipe to work with. The rear down bars were very long in my application, but the Jegs kit supplied enough pipe. Also was lucky to have a sales person that worked hard for my on my application and dimensions supplied.

Step up and buy a chromemoly kit or have a custom chromemoly cage put in the car now What is your life and body parts worth if you end up testing the cage like happened to Big Cheif on his street outlaw car Chromemoly has memory, mild steel does not If you race a lot chromemoly will out live mild steel by a bunch, a freind of mine found that out the hard way. He wore out a fast power adder mild steel car in less than three years of racing no more than 12 times a year, 10 or less runs per race I'm sure you don't want to hear about removing the roof to make the complete welds on all the roof bars but it is really worth it Do it right once

The first post provided the car we are recommending a cage for. That's why I recommended to not use a halo. Every time I steer people away from kits I get bombarded with pics of really nice fitting kit cages. Jegs was mentioned. I know a fellow who bought one for a Dart. It was horrible.

I have never had to cut a roof to weld a cage in. You can leave half the headliner bows out after my cage is in. I updated my car to 25.2, the first car to ever get the cert., headliner was perfect. Stuck the parachute cable through it and had to replace. Oh well.