OP, if you take 1 gram off the small end of each rod, then that drops the total bobweight by 1 gram. If you take 1 gram off of the big end of each rod, then that drops the bobweight by 2 grams; the numbers I suggested were for taking it off the bottom.
So that is why I suggested taking the weigh off the pad... by which I meant at the bottom. You get 2x the bobweight removal there. It does not matter if you take it off of the reciprocating or rotating weight. BTW, the beam is almost 100% part of the small end if you think of taking it off there.
When you grind it off, just do a small bit at a time to avoid heating the metal. You don't want to distort either end. Have the rod cap bolted and torque in place, and I personally would check the big end bore before and after. And the hole in the top shouldn't hurt....since it gets done regularly.
YR, he is trying to not do the balance work but to stay within the factory tolerance.