[Adger Smith]

Use a 1010 it pulls the fire ring back from the edge of the cylinder more and heat doesn't get to them as quick. Make sure that the chamfer on top of the cylinder is not too wide and getting into the edge of the fire ring. Lay the gasket on the head and check fit of the chamber. Extra porting might have chamber overhanging the fire ring. It can't seal when it is out in the combustion chamber heat.
Re torqur after the first days usage. I mean Torque it properly, don't just set the clicker and drop it on and pull till it clicks. Back each bolt up 1/4 to 1/2 a turn and in one pulling motion keep the bolt moving until it clicks. Torque should be reached while the bolt is moving. You are reading torque that way and not static friction loads of under the bolt head and the threads. Last...back the timing up from the 36 or 38 you probably have it at and keep it around 32-34 max.
Good luck