I had mine rebuilt by D&D and the timing mark was OFF TDC. Had to remark it.
Check out TA Performance. They may have harmonic balancers, I don’t know but I doubt there’s a diff. I’d go for a new balancer vs. rebuilt if available. They are willing to talk and have good info. They specialize in Hi-po Buick engines including the 215. They carry the correct oil pump gaskets, pumps, including HV and a booster plate for the pump, and a shim gasket kit for the oil pump so you can get the bottom plate clearance correct. Also new front covers of the Rover type so be aware they don’t have the generator mounting bosses.