I'd put TUPY head on as others mentioned. rent a valve spring compressor and give all valves and seats a look. check all the ports and make sure the surface is flat. may need to be decked.

also take care when removing it. take a torque wrench and undo the head bolts in 10-20 pound increments. go in reverse order as you would tighten it. popping head bolts completely out can warp it if not done with care