Got it
427 or machine one to neutral.

Thanks to all!!!!

Similar issue. Rebuilding a pair of GenV 540's. Appears the previous builder internally balanced the engines, but used externally balanced flywheels and harmonic balancers. Not sure how this happened, but might explain why the port engine spit a main bearing out into the timing cover after 200 hours. Anyhow, I need two neutral balanced flywheels. Will the 427 application work for me too? Thanks.

yes,396 or 427,both are internally balanced.

2 peice rear seal 350s will also work.

Even on the GenV one piece seal crank? Also is there a special pattern for the coupler? Thanks.

the one piece has a smaller bolt pattern
so it wont work..