New Cylinder Head, Now it won't start.

[mrlmd1]

I had this problem with a small outboard I took apart and put back together, twice, 'till I figured it out.
Any chance you have an air leak from a bad seal at the top of the head when you put it back together and when you try and fire it up, there's a small air entry through there and it's so lean it won't fire off? You should check that again, maybe need a new gasket or sealer in there.