with old bores i wouldn't use a piston with a straight pin. without getting the dial bore gauge out you'll never know exactly where your at. a piston with an off set pin will "cover" used bores better. think your stuck with the old trw clones. i'd look at a 2266 (think that's the right number) with a .022 steel shim gasket. shouldn't be a big deal to get compression in the 9's. may need a little off the heads, but should run on pump gas.