I found one on GB tonight, a 625 chambered .45 Colt, not .45 ACP.
$1195 buy it now. It would use, I am pretty sure, the same speedloaders that work for my Redhawk. That would still be a heap of grip to conceal, but getting the barrel shortened shouldn't be too bad.
http://www.gunbroker.com/Auction/Vie...Item=347507973