340 parts interchange & performance Q

I agree grab an early 318 or even a 273 forged crank and a early 340 balancer.
I dont think the Performer cam and intake will make as much power as the stock 340 parts would.

I would either use the stock iron 4bbl or an Eddy LD340 or RPM and a 650 Eddy AVS. For a cam the Comp Cam XE268 is a great step up from the factory 340 grind.

If its an automatic the Turbo Action "Medium" 10" converter works great for the 340 with 355s or 391s.