straight 6 to v8 help
These cars up to 67 also had an "inverted spring" front suspension, just like the early Mustang, where the spring rides in a pocket in the inner fender and the upper control arm has the load bearing ball joint.
Regarding the TH400: you'll need a different tranny mounting bracket and a very large hammer (read sledge hammer) as the tranny tunnel is not fashioned for it. I'd use a TH350 instead. You'll also need all the appropriate linkage.
While not a "bolt in" without the correct pieces, nevertheless it can be done. You can probably find the necessary parts from Classic Industries or the like.
I've only high lighted the bare basics to do this. The car is very light whether it's a "Nova" or a "Chevy II". Actually a Chevy II (which is a sedan: i.e., post around the door glass and not a fastback) is lighter than a Nova (which is a coupe; i.e., no post around the door glass and a fastback rear window style). I've had both a 67 Chevy II with a 250 six and 3 on the tree as well as a 67 Nova with a 283 and powerglide on the column (back in the 70's). I'd settle for either of them today.


