67' 318 crank in a 69' 340

Roger. And looking at the numbers again, it is to wonder if 13 grams could be taken off of the big end of the rod.... that would bring the big rod and KB piston right in on target.
FWIW... my numbers are very close but I would re-check one thing before using them... the small end/big end split on the lighter 318 rids weights. They might be off a few grams + or - which would throw off that 2147 stock bobweight a couple of grams.