If it was a rotating from scat cranks it would already be balanced. At least that’s the way mine came. With a scat harmonic balancer. Had machine shop mill counter weights and balance my old B&M flex plate. Engine runs like a top. Can’t say enough about scat cranks, they provided what they said and answered all my questions, no matter how stupid they were.
If you bothered to actually read what he said, it wasnt a complete "rotating assembly" bought as a ballanced kit. It was bought as individual peices, and that requires ballancing. Pretty simple