On the balance side of things I would get it done my scat kit I ordered and payed for balancing was 16 grams out my machinist had it within 2 grams. Engine runs so much smoother.
Did your machinist happen to say what was at that larger tolerance? Was it the balance between the piston/rod assemblies, or the crank balance versus the bobweight? More curious than anything.
IIRC..... SCAT says they balance to a +/-5 gram tolerance but it has never been clear to me which factor that is... or if it is both.
