If you wanna be extremely low buck about it...get yourself a junkyard head for as cheap as possible. Pull all the valves out and then try to find some Chevy 1.94 intake valves...or valve since you only need one of them. Use the 1.94 and a 1.60 exhaust valve from the head....buy some sticky back sandpaper like you would use on an orbital sander. Cut it to fit the head of the valve, slip it up through the head and connect a drill to the top of the valve stem and go to work. You don't need to cut them very much. Try to make them all the same depth and stay away from the edge of the piston if you can avoid it. This is as low buck as it gets for notching pistons. The end result will be a slightly higher compression ratio piston than you would get with the other pistons and it shouldn't cost you any more than it would to replace the rings when you swap to the other pistons. Or if you can get the Isky tools...sure, but they'll cost you a lot more and you'll get the same results.