To me it looks like just about every old TRW heavy slug - stock rodded engine after a few years of running! - the skirts on those pistons always seem to have had a funky edge on them from the forging process - we used to dress them with a honing stone. If it has good ring seal now run it if not - give it a quick dingle ball hone hone and run it - those pistons are pretty forgiving when it comes to clearence as long as its not too tight.