Hi Dan... another lefty here.
Barrel length has less a bearing on the "quality of concealment" than one might first imagine... IMHO, less so than the length or shape of the grip frame. 3/4 of an inch in barrel length isn't going to make you or break you.
I'm afraid that I am completely unfamiliar with a jacket that allows concealment of a full size handgun... not a clue as to where the gun is or how it's oriented or secured in the jacket.
Just to toss around some general considerations... both guns (probably) have a government length grip frame, but we don't know if either gun is round butted or bob tailed (less likely to snag clothing or have a sharp corner to "print"), or how wide the grip frame is on the double stack vs. the single stack (a minor point, but worth consideration with snug fit clothing)... so it's kinda hard to offer really useful advice without having more information.
Truth be told, as you're 6'5" and (probably) have a chest 15-20" larger than your waist... I suspect you could conceal both equally well.
