about 50% of the valve guides show leaking oil. I've talked about the valve seats to them. If the guides weren't bad I would have just lapped them myself.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.