Will a .30 piston fit in a standard bore on a sbc 350?

Was playing around out of curiosity and for the fun of it. I supposedly have a standard bore 350 block and grabbed one of the .30 over pistons off the shelf, compressed the rings a bit and it slid in the standard bore. Is this possible? Have'nt taken the block to the shop yet to verify bore but was just curious. The guy I got the block from was pretty sure it was std bore but who knows when you work with craigslist.