An updated Model 44 with full length tubular magazine, if possible make it dual tube like the KSG. Available in .327, .357, .41 Mag, .44 Mag, and .45 Colt.
Dump the wood stock, I'd rather have a polymer one like on the PC carbine with LOP adjustments and cheek pads.
EDIT: Oh, this is for revolvers. Uh, the Lightweight Service Revolver, which is basically a larger LCR around the size of a Gp100. Not my idea, but I love the idea because you could have a 6 shot .357 in a GP100 size revolver and it'd likely weigh 30oz. A 10 shot .22 and it'd probably weigh under 30oz. A 5 shot .44 Special LSR that weighs 25oz and has a trigger even better than the LCR due to the better ergos.
That would be a Charter Arms Bulldog killer.
Not just the weight, but the price would be lower too. The LCR's cost less than the SP101 and while some may be willing to pay for a small steel revolver for CCW, the larger size revolvers don't appeal to the casual crowd for any serious use besides the big gun machismo thing.
-A 10mm Magnum Blackhawk with spare .40 S&W cylinder. If I'm gonna shoot rimless 10mm in a large frame revolver, I have no interest in being capped with 10mm Auto and I don't feel like paying extra to have someone ream the chambers for 10mm Magnum.
-Adjustable sights on the 6 inch Bearcat