We have to run 1.75 DOM in our car.

Don't worry, we are all adults here on this forum.

That said, I am not a big believer in speed as a useful indicator of what are the best materials or design.

In that all concrete is fairly consistently hard, and #3 Dale died hitting concrete at an effective closing speed of approx 43mph.

I saw a race where from an on track cameras showed Richard Petty’s car just barely touching a wall. Nothing much, but the in car camera show him almost come out of the seat, arms and head viscously moving in the direction of impact like a crash test dummy.

I built 2 dom steel cages 15 years ago for a guy, welding method wasn't specified in their rule book, the only method I knew back then, was Stick welding with root and cap, the mig I had back then wasn't beefy enough.. I did a gapped fit up with a 6010 root, and then a 7018 cover pass.
The guy ended up hitting a large tree with one of the cars at high speed in passenger side frontal impact. None of the welds gave, the tubing bent and the frame rail sections ripped out of the unibody in places. The driver and navigator walked away from the crash. Weld porosity is a big problem
with stick welding, done wrong, its weak, done right, really strong. We use it a lot in plant construction, but we also have to do 10% xray on joints.
Porosity is pretty much non existent with tig, but can have shallow penetration and be a very pretty, but weak weld. Easy to undercut the joint with too.
When I do my cage for my next track car, I'm probably going to do a tig root and Mig cover pass. I don't build cages for people anymore with all the liability stuff...

I'd never even think of welding a roll cage. I do a lot of bench welding and I can make a nice bead when I have my arms in the right position but there is zero chance I could get nice welds when I'm laying on back reaching around a corner or something like that. The chassis guy that did my cage really had to work to get to a few of the welds. They tig welded the cage and on some welds he had a helper run the foot pedal while he handled the torch and rod. Those guys work as a team and do that type of welding all the time. I never do that type of welding and I'm not going to start on something like a roll cage.

You have to plan the job and how it's going to be put together. Some of it may be partially welded and pulled out of the car to finish. And/or it may be dropped through the floor. Or, like a lot of cars with funny car cages, etc., cut the roof off.

The chassis serves two purposes. Protect the driver and be the main structure of the car supporting the suspension with the desired rigidity.

The rulebook spells out minimum requirements. They are seldom sufficient to do both jobs well without adding to it and improving on it.

Thank you everyone! The information I received here was incredible. I never would have though up all this stuff. Even though one car would be more of a 'cosmetic' thing, I am going to completely rethink what I really need in a cage and see what fits my needs. I am starting out with the worst possible car bodies with this build (burned b-bodies) but enjoy the challenge of something different. I'll see about checking out pre-bent cages, a professional fabricator that could adjust/modify the cage to accommodate my needs. I'm thinking of going to Chris Alston's Chassisworks and see what I could use for each car (they are a short drive for me). Skimping on safety was not my intention. Finding a way to come up with the extra cash is far more easier than the added materials/work required for the job. Thank you for your info everybody, I feel this has enlightened me to a better understanding to my needs for this build.

I used Art Morrison for my 10 point kit in my Dart.
I used a Competition Engineering kit for the 6 point I had in our last car.
And if I do another , I will have learned enough to do it better than the last one.
Hindsight tells me I should have gone through the dash and created much more room to get in and out of the car.
But if I did go that way , I would seriously consider an experienced fabricator to do the job for me.
My welds are Dog's Butt ugly , but I trust them.
I use mild steel so I can MIG it , but the tight quarters and awkward positions required were much less of a problem , even in my 40's.
That was twenty years ago.
It's not the place to learn to weld , that is for sure.
And you can save a lot of money by mocking it up and doing the fitting your self if you are going to have it welded by a pro.
The guys I use for stuff I can't do are around 100.00 an hour and well worth it.
And the fitting is the time consuming part of the project.

Burned? As in on fire? Bad? Not a good choice for so many reasons.

A professional is not going to use a kit. Most won't anyways. They prefer to do it their way. Kits are for guys who have some fabrication skills but no bending equipment.

Well, it will be lighter. Like I said, these will not be typical cars. One for track use, one for street strip. If worse case happens, I can always just move onto another shell.