. . .
Just to iterate what I have been learning from these discussions:
There are very few vintage regs that are considered recommended for cave diving, the ScubaPro MK10 / G250 being a recommended configuration, the Dacors being not recommended.
Yeah, I figured that might be the thought process that led to this thread. Someone recommends old SP regs, and now you and your buddy are wondering whether other old regs might also be good.