Tim, I was thinking about your comments about the tall gears of the era. I bought a new Baracudda in 1965. 235 hp 273, 4 speed and 2.25 or so gears. It would do about 45 in first, 80 in second, way past 120 in third. Who would know in 4th?
My 251 will be barely half the hp, might not push that tall of gears so well. It's become obvious I should chech the ratios before getting too serious about it.
However, it's pretty simple to stick a rear end in and find out how it works. Probably have to invest in a driveshaft unless I could get the existing one to match some way.
I have swapped rear ends in Chebbys, just torch off the coil spring junk, cut the mounts off the old rear, weld them on the new former coil axle, bleed the brakes and drive away. U joints matched on those, probably not here.