building a 383 Stroker with Factory parts help needed

Grinding/milling on aluminum parts (especially) is asking for stress riser issues. The spread on decent parts is almost always less than the 6gms or so Hines(etc) specs for oil weight variance. Engineers, competent ones anyways, spec certain surface finishes for generally good reasons.

Unless you're going from light parts to heavy, like aluminum rods back to steel, you're almost never going to need to add metal to a mopar crank. Generally, the machinist is pissed that he's going to want/need to lathe turn the damned thing because it's needs 200+ gms remove and that's some serious drilling.

Generally, most places price jobs they really don't want to do like what you were quoted, rather than just say "no." Only in rural areas, generally, is the price of competent labor low enough to justify turning consumer type cranks. Even the big diesel shops are selling off their crank grinders because UPS/FedEx or the trucking company is far cheaper than an experienced and competent machinist. Now if I were God-Emperor, trucking would be expensive because about 25+% of steering wheel holders would be deported or blacklisted from ever holding a CDL, and 50% plus of trucking company executives, brokers and managers would simply be hanged but that's another conversation. S/F....Ken M