Buy a box of these, mod up some 440 valves to act as fly cutter notching devise, the crank and rod idea you chose is good. The UEM 1278 piston with a compression distance of 1.658 and the notches you create yourself in a Poly will give you more working room than what I did to this LA. Also you'll buy a crank instead of having the mains turned down and counterweights clearanced (blue inked area).