It's totally dependent on what piston you're using. Factory cast style pistons require much tighter tolerances than a forged piston in comparison, so if she's using a factory cast piston, the "go no go" tolerance for bore should be adhered to by what's written in the factory service manual. If she was running a forged piston, they require a good bit more clearance, since they have a greater rate of expansion. I believe she is going to either use the original cast pistons or a factory replacement type cast piston, so she needs to pay attention to what the factory service manual says.
