forged crankshaft

You should be able to achieve what you want with a bit of margin. What piston oversize do you plan?

We used a 273 cast crank in my son's 340. Added SCAT rods and KB's. Bobweight was 1893 grams for .020" oversize pistons, compared to the nominal stock 340 bobweight of around 2308 grams. Took 81-28 grams off of each end's large counterweight to balance the 273 crank.

With the light SBM rods you ought to end up a bit over 2100 grams of bobweight, depending on piston oversize. Nominal bobweight on 273's is right around 2117 grams, so you ought to end up just under that. It won't take much metal removal to make that balance out.

If you used the heavy SBM rods, you would end up about 45 grams heavy on the bobweight for the 273 crank.