The SM 318 3 speed that was in your 54 wagon and also in his truck was actually used until about 64 behind some pretty healthy V8's including the 348, but nothing's bulletproof, given a sufficient amount of right foot. I got really good at swapping 3 speeds in a buddy's 55 Chevy 2 door with a 301 V8 in it (4" bore 283 that Chevy called a "302" a few years later). It's more likely that he will corkscrew a driveshaft or twist off an axle shaft. The 41 coupe had a tiny gearbox that actually had a tendency to completely wear out to the point it couldn't be rebuilt, running behind a 216!
Jerry
