If they are "mostly a chevy shop" and cannot get a bbc sized bushing for you, I'd look for another shop. If they do any type of high performance work, they should have suppliers for either the part or the stock to make the part. If the shop is having you chase down the part, then he is also going to blame any future problems on your part.

Also, did this shop look at these parts before the motor galled up the wrist pins? I'm not looking for an answer, but if the answer is yes, think about that before having them do the work.

Good Luck