273 dilemma

As long as you're not going for a mega horsepower build, you can use just about any 273/318 crank. Regardless of which one you get, I would rebalance. The '64-7 273 crank would be the same as what you have....forged and with the small converter register. A 318 can be found in either forged or cast, both are internally balanced just like the 273 crank, so, rebalancing should be minimal. If you want a forged crank for added strength, look at a '62-7 318 crank. Those were all forged. '68 and later 318 forged cranks are mostly found in trucks and vans (and some industrial engines) mostly with a manual transmission. If your horsepower is below 400 HP, the cast 318 crank will work just fine. As mention, get the converter register bushing for a stock early 273/904 converter button. I used to have crank thrust surfaces welded back up, but, finding a machine shop that will actually do that work these days is getting hard to find, and the higher labor rate is something to consider too. I just had the same problem with my build, but, was lucky enough to have a spare crank. I kept the original crank in case I find a machine shop that will repair it for a reasonable cost.