The HP was pretty much designed around the 9mmP, so not enough room for anything longer. A 9mm 1911 would be an easy conversion. Seems like there were some variants of the CZ75 that were offered in .38 Super. One of the Tanfoglios maybe? Anything with enough room for .38 Super would work. I have been reading posts in other locations on the 'net about people converting Tokarevs, and experimenting (CAREFULLY!!!) with guns chambered for the 9mm Largo. Pretty intriguing stuff.