I am still in the planning stages of the motor that will replace the tri-power after I get some paint on the 64. The current plan is a 200 ,9 to 9.5 to 1 compression, C.I. alumunum head and a 50 or 75 HP shot of N2O. givin a this basic combo and a 5200 to 5400 rpm max redline would cast pistons hold up? This will be a street engine with an occasional 1/8 th mile run or short burst on the backroads. This is my weekend cruiser which I occasionally drive 100 or more mile on a weekend to shows or cruisins. I have read that Mike has been looking into getting some Hypers made at a very good price but all research I have done has been conflicting, I have seen a lot of bad press on the keith black hypers being stronger but more brittle than cast and having less thermal transfer effieciantcey which causes failure with boost. can anyone shed light on the differences between cast and hyper in terms of strength , resistence to detonation , longevity with higher rpm and N2o. I was trying to stay away from forged so I can run a closer skirt clearance for ring control and longevity since I want this engine to last.