Head Gasket Question
if you really love and want to keep the car and engine the best bet long term is expensive, but worth it. engine pull > piston swap or maybe your builder can modify your current pistons to enlarge the cuts in them and increase the cc's (depends on which model wiseco's I think).
you might be able to sell the pistons to recoup some of the money.
a thick custom head gasket might do the trick like you have considered. cheaper than a piston swap, but still not a freebie. and it might not lower the cc's enough.