Most people, probably that machine shop also, have spare bolts laying around from when they built there car. If you've had a problem with buying a complete engine then you might want to think about reusing whatever is good on your motor and just buying the parts you need, atleast a crank, oil pump, rebuild kit. Then have your machine shop rebuild it for you. He could take a look at all your parts and tell you if they are still in good condition.
I don't have any 7 bolt stuff so I can't help you out but I see the stuff on Ebay all the time selling cheap, as long as they have over 10 + feedback and no - feedback it's probably safe. I've had 1 problem with almost 150 buy/sells. You just have to look at it and ask yourself if it looks legit.