Here is a rotating assembly that I used in my Duster engine. This was a low deck with a 4.250 stroke Callies crankshaft, 6.535 Crower rods and then a set of semi-custom pistons from Diamond. We had to turn the counterweights down on a lathe but I don't think the crank required any metal to balance. I think we just had to dimple it and it was good to go. The rotating assembly was fairly lightweight. Around 2300 gram bobweight I think. This was a fairly expensive engine to build. These days with an RB block I'd use a stroker kit with 6.800 or 7.100 rods and call it a day.