I know that when you get into the changing of the cams you might need to change the parameters of your ecm, how that gets done on a four cylinder I don't know. maybe a computer out of a 4 cylinder SVO, turbo 4 or something. pistons you can match bore, pin, stroke specs size at any speed shop and buy aftermarket but I have to ask why are you doing all this to a four banger? Insurance or gas mileage?