Nice Job. Did you trying figuring out what the axle length would have been if you got another long side Explorer axle?
Betting you did, but it isn't clear from the write-up.
It is really common to use a 90s Explorer rear axle in old muscle cars if you use two short axles and narrow it. The width is pretty good for many old cars. Posi, 31 spline axles, beefy, disc brakes and a great parking brake, those axles have a lot going for them. Same bolt pattern as early Ford, Mopar, AMC. Probably the cheapest way to get a great axle.