340 build question

cudamark said
If you use the 340 only cast crank, yes, you will need the correct balancer and flex plate or converter to go with it. If you're getting a stock forged 340 crank, your 273 balancer, flex plate, and converter will work fine. As mentioned, if your 904 trans is '67 or earlier, you'll need the reducer bushing for the crank to match the button on the converter. You can also use your 273 crank in the 340 without any other major changes. Just get everything balanced during your engine rebuild.

I'm unsure I agree. The 340 crank is neutral balanced, but it gets there differently than a 273. The 340 crank had gundrilled first and I think last crank throws, so the 273 stuff, although neutral balanced, gets there differently. It'll be best if he balances "whatever" he decides to use.