....Cancun Tom, greetings. A company (B.R.P.-Bud's racing products) made an adapter (pan car to hex)-several years ago .Though I haven't seen any on ebay, these adapters may be around somewhere.
Try logging omto TeamCRP- they have the opposite adapter( 4-bolt to "pin drive" ).
...if you get a chance to look at these pieces(two per pack) you may be able to 'modify' the plastic pieces into a hex - i heven't tried this myself but you may find a way to utilize these pieces.
Good luck.