Carb Problem?

As part of a separate transmission cable replacement issue, I decided to hire a mechanic to rebuild my gunked up carburetor. In hindsight, I wish I had done it myself, but that is another story.
The engine now fires up on the first crank, but it wants to rev up high, and there is a lot of blue smoke coming out of the exhaust. There is also what appears to be a gas slick forming on the water behind the exhaust. And it sounds like it is spark knocking.
The oil pressure is 40 psi. No water in the oil, and the level hasn't dropped. The plugs look ok, except for two that are a bit black and dry(I am assuming from having to run it for an extended time with the choke, from a gunked up carb?).
Now the cabin of the boat smells like gas, and there appears to be a gas-like residue on the OUTSIDE of the carb and underneath it. The mechanic swears that there is a valve or piston problem and that the gas slick is an oil slick, but I know for a fact that it wasn't smoking/knocking/slicking before the repair.
I would greatly appreciate any insight on this problem. I will be checking the compression on the next trip down to the boat.