Since it's a revolver and feeding isn't a problem, the best bullet would be a WFN and I would lean toward at least a 260 gr. A 280 gr would be even better if the cylinder length allows seating out to maintain optimum powder room. Use the rimmed brass so you can crimp, or bullet pull will be a problem. No need to try to magnumize it. You should be able to get even a 280 gr out at 1100 fps with mild pressures, and that will knock Bambi on his canister with a delightful suddenness.
As for the Whisper. There is not a good 30 caliber big game bullet for 1100 fps. For all of you who are interested in subsonic supressed loads for game, please understand that there is NO advantage to a silencer on game, because. With the report, which is very audible to game, your location and distence is proclaimed from the house tops, and they are instantly running at full throttle if the bullet doesn't hit an instant kill nerve. In addition, the whack of a bullet against game, when there is not a loud muzzle blast to hide it, is heard, and everybody in the area is off with the wounded critter. You don't get a chance on a second animal because of a suppresser. (On the other hand, if the firearm makes a loud report, game is confused as to exactly where it came from, for a few seconds at least, in which time they die if the hit is good and the bullet performs well. Consider what I'm saying if you are thinking suppressor, and don't forget to add in the ATF permit fee, every year forever, and likehood that they will come checking on you if there is a crime done anywhere near where you live. Even if it's murder with a shotgun, for pity sakes!)
Of coarse there is the very real advantage of being able to hunt where loud gunfire would irritate people, in which case a suppresser has real utility. I've taken something around 10 deer using one, so I do have hands on experiance. The best bullet I found was my WLN, wearing a softnose and with a 60 deg included angle hollow point drilled into the tip to induce instant expansion at the low impact speeds. It consistently punched a 1 inch diameter hole through every deer I took and all were with chest shots. Even steep angle shots exited, and no deer ran more than about 50 feet.
I've made quite a few 'heaviet possible' spitzers, with as much boat tail as I could make, but have never had a single sentence of feedback regarding accuracy or anything else about performance. So, for right now, I'm recommending a gas checked bullet, simply because most customers will wring a bit more accuracy out of a gas checked, compared to plain base, and precision shot placement is VERY important with low power bullets. If a customer wants to use a graceful spitzer to get maximum B.C. I can make them, and would recommend the use of tin lead, 20-1 and hollowpointed with a straight hole. If this option is chosen, experiment with depth of the HP until the expanded bullet, shot into water or wet news print, is about 1 1/2 calibers. I'd recommend a 3/32 diameter drill for the HP.