I don't understand why you wouldn't use a Muncie M21, M22, SM420 or SM465. Those are some very stout transmissions and I guarantee they can handle the power.
I have a 427 in front of an M21 in my Corvette and it's a wonderfully shifting piece that works really well. The M22 is a rock crusher, of well-deserved drag racing fame.
The SM420 and SM465 are top loader rock crusher Muncies and are just about bulletproof. I have an SM420 behind a strong 350 and it works perfectly. I've got an SM465 out of a seventies tow truck, but the 420 works so well that I don't really need to change it.
The only reason I can see that you don't recommend them is because of the lack of an overdrive, because it certainly isn't because of strength. You can overdrive a Muncie if you use a Gear Vendors overdrive tailhousing. Then every gear can be electronically overdriven.
