340 Piston to valve clearance w/RHS heads
Hypereutectic pistons deflect heat towards the chamber and they grow less=require less skirt clearance.
I've used them off and on for years with great success and have not blown a hole through one yet.fwiw
Seems to me there are a lot of knowledgeable people here giving sound advice, some however is not.
None the less...most of it is falling on deaf ears.