Interested in how your doing this, sounds like a cool project. Hope it goes well for ya 
A little update, well, pulled out the Mopar housing ends I got from our friend Cass, took all the measurements I needed and trimmed the old free float housing ends off with a metal drop saw, took a bit of time to make sure the saw was going to cut a good square cut to minimise cleanups. the Mopar ends are 2.5" long so a little math and good to go to end up with a flange to flange housing length of 54 7/8", (a 1/16" shorter than a 1970 B Body as I wanted to pick up a small amount of outer fender lip clearance) I then borrowed a housing jig from a mate, large diameter solid steel shaft, has two sets of 'donuts', one set for the carrier bearing location so bolt them in tight, the shaft passes through so the other two donuts fit on the shaft and fit into the Mopar housing ends to keep everything in relative alignment,,,,sort of anyway.
Sooooo after some more carry on, I manned up and welded the spring perches (44" apart) with a pinion up angle of 7 deg, this matches a std E Body housing angle. then tack welded the housing ends onto the Dana tubes, these Dana tubes are thicker than 3/8" wall thickness!!!!!, so after tacking in four spots I then got out a couple of 6' levels to use as straight edges and clamped them across the ends of the housing and measured either end to check for parallel , they were within 1/64” then did the same 90 deg around to get the same so pretty happy with that.
I’ll take it now into a mate who owns a welding shop to have the ends receive full penetration butt welds, the spring perches welded on and also have the axle tubes welded to the cast pumpkin.
That should have the housing set up for the Cuda but with B Body length specs to match the 8.75 unit that is in it at present.
I’ve got axles with screw in long studs from Cass, a Strange S-Trac centre, 3.73 gears and a 1350 yoke, once that’s done I need to have a driveshaft made and good to go
