I bought a motor while i was deployed in iraq back in the day from jasper rebuilt motors that was suppost to have been 1989 factory spec which came with forged pistons and roller car. so five years down the road i got 3 bar heads and i seen my pistons were four valve relief but were cast according to the part number on the piston. Jasper told me to screw my self and factory spec was just a size to boot they installed a flat tappet cam in it. 60 over isnt factory or the flat tappet. I like my 311cubes. but now i have a edelbrock plate nitrous system im just sitting on. Could i use a 75 to 100 shot or am i going to burn holes through the pistons. Im unsure to take them to court because i cant prove i havent change them myself with the time lapse. BEWARE Jasper motors are thieves and shisters.