340 crank..junk or saveable?

The problem with grinding cranks way undersize is two fold. Crank journals are induction hardened. It only goes so deep like case hardening. You can get bearings up to.06 under but those past.03 are Chinese and you may not be able to trust the quality. The other problem is the corner radius or the under cut on a mopar crank. You could also have the rods ground for chevy size rods, that is another option. Most machine shops that service big trucks and construction equipment are well versed in crank repair unlike most run of the mill automotive machine shops.