B Body automatic to 4 speed conversion question

Hi! I am in the process of converting my 70 Coronet R/T to A833 4 speed. Regarding installation of the shift tunnel-the "hump'. I've seen posted, and been told in person by those who've done it, the tunnel just fits where it's supposed to go.
In my case, kinda.
I'm using an AMD shift tunnel, and by tweaking it a little here and there, I think now, it fits in the correct position. My question is, is there a reference article or posting anywhere,that gives a correct dimension,perhaps from the driver's door pinchweld, to the center of the shifter hole? Same from the firewall/floorpan pinchweld to the hole center?
Also, when cutting away the original floorpan beneath the shift tunnel, do you trim along but not cut into, the crossmember? How did the factory do it?
Any help or advice appreciated!
Thanks, Paul

The hump pretty much does find itself on the floor, but IMHO your better off just mocking up the 4 speed in the car, throw just the bell on, slide the tranny in with the shifter box and crossmember mount, and locate the tunnel shifter hole spot on, esp if your doing a benchseat shifter, then remove the 4spd when your ready for complete surgery/welding...

As far as the floor under the hump, I like to leave as little past the flange of the hump itself, the 68-70 B body hump isn't that large, you need all the room you can get, and there's no cutting of the torsion crossmember, however, clean up any burrs or sloppy overlaps/seams along the exposed section of the torsional crossmember with a grinder before you seal it under the hump, some extra welding on the torsion crossmember sandwich construction wouldn't hurt either as long as your in there, be sure to seamseal/paint your surgical work as well...

Mike

Thanks Mike! I totally agree with you, a mock up is best. The engine is currently out of the car, but the winter is long, and I have time to swing the engine in,along with the bellhousing, transmission,and rear crossmember,and be sure. I'm afraid of an unwanted "surprise". A trial fit is best.
Also, I had the opportunity to look at a friend's 70 Roadrunner, a factory 4 speed car.This car was pristinely painted, awaiting assembly,I could only look in the window,but he carefully crawled inside, and gave me some measurements, I couldn't see underneath, but I did notice, that the hump was welded, with 1 1/4" to 1 1/2" long beads. and a similar gap between the beads. The welds were along the hump's edge to floor. Nice n strong.
Thanks!
Paul

i have a section of floor from 69 RR that i use to lay out floor hump.can't get any closer then that.