well, basically you gotta check the head out:
if you can get a machinists straightedge and a feeler gauge, make sure the head hasn't warped, or have any cracks for that matter, and if its ok, get new head bolts and a new gasket. Really, the big expense is replacing all the stuff you should probably replace when you've got the head off.
Worst case, a new head is small enough (we have teeny engines, after all) to be mail-ordered.