My readings are between .497-.498. Generic ones seem to measure right ar .500. Now that may not seem like much difference but in a press fit situation the generic ones will not go into the holes in the block or the case. I have some older Mopar performance offset dowels that I used to correct alignment and they fit just nice.
one could easily file or sand down a few thousandths with some sand paper. just chuck it up in a drill. you wouldn't want any more than a few 0.0001" interference fit, if any at all.