OLD SCHOOL ANSWER. If you want to copy what was done back when 57s where what almost everyone had, and making some serious torque read the following ramblings. In the mid to late 60's we used 55 to 59 buick olds pontiac station wagon rear ends because they are the same width and only required a few changes, twelve bolt or stronger and cheap. The changes we had to make were to the driveline yoke spud, axle bolt pattern, and on a few, the spring saddle location. I used these successfully in many 55-56-57 stock cars (I know you did not want to hear that, but they were a dime a dozen back then and many times free) never breaking a rear gear set except in a bad crash on a 1/4 mile oval track. The very best was a 59 or so Buick roadmaster wagon, as it had finned aluminum 11" x 2" drums that were non-servo like discs. These also had 2" axles at the flange and with axle retainers NHRA allowed them in A mod production. As a side note the fronts were 12 X 2 and almost a bolt on.as well as being non servo. I realize that these are unobtainium now but if you find an old salvage yard take a look. We built a lot of rat rod sleepers using the whole running gear with the J2 394 (tripower) engine being the favorite. These rears even held up when used with the hard to find three speed BOP manual trans set up. The last short track stocker (1/4 mile) I used one of these in was in 1978, running a 350 chev that put out some where around 300 corrected "guess" horsepower on my go-Power dyno. (hundreds of pulls and I don't race dynos). No one ever "pulled" me down the straights. I realize that you need something that is not quite as hard to find, so look for an older 9 inch ford ECONOLINE V8 as they are close to the right width and usually have the 31 spline axles. As for a mild low torque engine with an auto trans. most of today's full size V8 truck rears that fit will handle anything except a severe Wheel hop burnout. Have fun, ONIA.

my info shows 67-69 camaros and 1955-1964 chevy cars have 60 inch width. Spring pad locations may be different.