If you want the head gasket to seal, use the OEM gasket and don't worry about the increase in CR from the head milling. The head gasket joint is highly-engineered. Anyway the sight increase in CR will yield a slight increase in performance. Also, make sure the machine shop has experience with the Toyota head because the 1zz does not have valve seat inserts. The seats are laser-clad and I seriously recommend not allowing them to machine the head for inserts. Anyway, the seat material is really tough and probably will be fine with just lapping. I also would not change guides if they are not worn. Make sure you follow the head bolt tightening procedure in the shop manual very carefully when reinstalling.
