Wow, nobody replied? That's weird.

If it's still off, here is what I would do: Make sure the pan surface is flat by using a straight edge. If any of the bolt holes are uneven, meaning they are high points on the sealing surface, flatten them gently with a hammer backed with a wood block. Clean the he!! out of both sealing surfaces. Use acetone as your last step. Use permatex sparingly on both metal surfaces and put the gasket in between. Do NOT overtighten the bolts. I'd use a t-handle to make the pan contact the block and set the bolts to 'less than just barely tight,' wait an hour or two, then torque them to spec, which is very low.

Hope that helps.

John B.