Find out what caused the failure first, so you can get a plan to go from there. After the engine autopsy, you may find that heat was part of the problem, & that you needed far more cooling for engine & trans.
.... I remember all those pull over water stops on the highways back in the 1950s & `60s - so even the Buick with the factory tow package was heat stressed back then on Southwest desert grades!
The racer cam probably made it run even hotter I would think, while the towing/hauling cam & other suggestions above would keep it cooler by staying in range.
My uncle in the 1960's had a hot rail dragster with a GM 400 bored, cammed up, blown & pushed to its limits - and he rebuilt the motor just about every race or 2 or 3!!
PS - when you go back into the 50's & 60's - it also opens up a whole new arena of vintage kin which are still silver twinkies, but with different features & often better built that AS, such as our Avion, Silver Streak & a bunch of others from the TT heyday! So maybe look at some other options too.
Tom T (janabanana48's other half )
1960 Avion T20, #2 made, Hensley Cub, TV tbd- looking for 08-14 Cayenne S
1988 VW Vanagon Westfalia CamperGL (Orig Owner)