If your crank is good put some new bearings on it, new seals, gaskets, and pressure check it after it's assembled. If your got a little dough left timing plate, cut your head or pro design, maybe some good porting. A good port job on a stock stroke will make way better power than a 4mil, I don't think you are going to want to spend what it takes to build a 4mil the correct way like no spacers,head w/custom domes, pistons, crank, porting,the list can go on and on and that's why most of us are here cause it's like crack....that's what I been hearin'...