Alternator woes

OK, I picked up a Chrome 1-wire Self-Energizing 100 Amp Alternator on eBay I went to install it this afternoon and it doesn't fit. I mean my upper pivot bolt that screws into the head is a 7/16" long shank bolt and the hole in the Alt is only 3/8" the other threaded bolt hole is also smaller than mine. Does anyone know what the correct bolt size is for the Alternator. If you look at the link it specifically lists 75-78 Mustang II w/302. The seller is willing to make it right but he says he's never had this happen to anyone before. Can anyone think of any options.

PS I can't drill the hole out to 7/16 because the chrome would probably start flaking, and then he won't take it back.

auction listing link

Yeah, I went through his feedback and emailed some of the recent buyers of the same Alternator. And of the 3 that replied 2 said they had to drill out the hole for the 7/16 bolt, but that other than that it worked great, the other hasn't tried to install yet but I assume he'll have to do the same. The funny thing is nobody until me had contacted the buyer about this.