67' 318 crank in a 69' 340

"I read somewhere that in '71, the 340 compression dropped from 10.5 to 10.25."

Very possible, going off memory here. But anyways, 72 was the big drop in compression.

Yep, looks like a forged crank you have there but the low comp pistons. Man, how could someone cut the crank like that? A good welder may be able to weld that up with nickle rod. Would need some good preheating prior to. I would probably give it a shot if the journals were all in good shape. If the journals have already been cut and possible needing to be cut again, would be best to start from scratch.