Huh. I have one of those. A Dacor Olympic from the early 70s (I think it's an Olympic 400). My father gave it to me the same time he gave me his old MK5.
You think anybody out there can still service one of those Dacors? I've never even tried to use it... it's about 9 years older than my MK5 and hasn't been serviced in about 30 years. I keep it mainly as a conversation piece, but if it could be cleaned up to serviceability... hmm.
Those are pretty generic regs. It would make a great first DIY reg, as long as the diaphram is good the rest of the parts are generic to most regs of the time (and a lot of low end modern ones as well). They are simple and easy to repair. Or to more directly answer your question, not likely a shop would do it due to the lack of OEM parts (and the liability BS that goes with it) but there is no reason not to do it yourself and learn from the experience.