UPDATE:
2 months into this thing.
I finally got a call the week before last that basically said, "I'm clueless, I can't figure it out" so they sent the boat down to another shop a few hours away.
Left me a VM yesterday that it was up and running and to come pick it up.
I called him back today and he said it's good to go and that I should stop by tomorrow when he's there to get it and to settle up. I asked him what "settle up" meant, since I already paid for a carb rebuild and tuning, and that he was merely finishing the job... slowly at that. He said that he was being as nice as he could, and that he knocked a ton of hours off it, but it cost him another tank of gas and 3 oil changes, and a lot of hours. I explained that the tank was full when he got it, which should have been about 3/4 of a tank more than any other mechanic would have needed to rebuild and tune a couple carbs, and that the oil also was fresh... and then re-freshed after his first gas overload. He said that it was an incorrect gasket that kept causing it to run into the oil, and that he had to keep changing it. Apparently, the fact that HE put that wrong gasket in, and the fact that HE used all the gas didn't mean anything....

Am I way off base in thinking that not only should I not owe one more dime, but I should be getting something back for not having my boat for the last two months... especially after I was quoted $500 and "about a week" and am now up 2 months and about $730 the first time plus another request for $350 more... what a joke.