If its not making a seal, you're either going to have a vac leak due to unmetered air entering behind the MAF or you're going to lose coolant. Both of which are bad.

If you know what you're doing with an easy out, do what scotty said, if you don't know what you're doing, take it somewhere and have it done for you. If you attempt it and fail, that's going to make it a pain for whoever has to try to fix the mistake.