No way to be sure if it was honed for cast or hypers or forged (I would assume with that good of work either #2 or #3). Anyway you could find out what pistons it WAS sized for? A person could have a shop mike it & I would call one or more of your local machine shops & pick their brains on this one. Never ran into this before! Here's a BTT for ya

live every 24 hour block of time like it's your last day on earth