How deep is the defect? That ring land carries a lot of the thrust on the piston from compression and combustion pressure, and it's stressed 60 times per second at 2K RPM. I would use it, but only as a paperweight. There's no way I'd put that piston in an engine. When we built up John's 261 a few years ago, we ended up buying two individual pistons from Rock Auto. One had a broken ring land, and another had a crack in the skirt that was discovered during the cleanup job. If you match the weight of all the pistons down to within a couple of grams (which should be done anyway) the engine won't care if an off brand piston is used. A dollar bill weighs one gram, and the race engines we built had all the moving parts weight matched to within 1/10 of a gram.
Just checked the Rock Auto website- - - - -they list a "single piston" price for both Silv-O-Lite and Engine Tech, but when the item is selected, it adds six to the shopping cart. You might want to give them a call and see if they'll ship a single.
Jerry
