I have large hands (but not that large) and I have learned to adjust my two-handed combat grip so that I can manage sub-compact pistols pretty well. It's a slightly different grip with a revolver, because you can't position both thumbs forward, due to the normal 'leakage' between the cylinder face and the forcing cone.
So, the best way I've found to grip a revolver is to clamp the weak-side thumb back over the wrist, right at the base of the strong-side thumb. You still do the 'push-pull' thing (push with strong hand, pull with weak hand), so that you aren't really having to grip it like a vise with one hand. Because you are pulling with the weak side hand, and clamping with the weak-side thumb, you don't have to squeeze so much with the fingers on your strong side hand. You are pulling it into the heel of your strong side hand, so you get a firm platform that allows you to operate your trigger finger independently from your grip, so that it pretty much eliminates the tendency to 'milk' the grip.
Clear as mud?
I use Pachmayrs on my GP-100, and they work fine...but then, I can't palm a regulation size basketball, so your mileage may vary.