The ones on Ebay i'm leary of being over bored
Most all of the GMC blocks are very thick, and can be safely bored .125" over their stock bore size. I know of several 302's that have been bored .125" over for Bonneville cars and drag racing that never gave any trouble at that bore size. And as Beater mentioned, a 270 can be punched out to a 302 with no problems either, and are still thick enough for further over sizes beyond that.
