318 LA rebuild after losing a valve seat

AJ....I know the deal here.... Press pins save about 2-3 grams as the pin locks are not there. The pin weights are identical for both: 154 grams before and after the rod change.
No, there is nothing close to a 100 gram change with this rod change in the balance area. And the production 318 LA crank was cast from day 1 for standard cranks, and the 273 used the same cast crank starting in '68. The 273's smaller pistons weigh less so they used 221 gram pins to keep the same bobweight. Both cast and steel cranks in the 318 are the balanced to the same bobweight .... I have never run across a different piston or pin weight for any model.

No more guessing... Bring real numbers if you want to try to convince the OP that he has a balance problem.