I just got done reading this thread. You've got a great price on the .454 buy it.
Don't worry if it's perfect.
Here is where I ruffle a few feathers. Shoot .45 Colt out of it, period. If you can't get it done with heavy .45 Colt loads, you need a bigger caliber, not more pressure. The .454 was an answer to a question 40 years ago, and the heavy .45 Colt was neck and neck with it back then. Casull wanted a flat, long range hunting caliber, with relatively light bullets compared to Seyfried wanting a big, heavy bullet for close range encounters with big critters.
You can load .45 Colt to be long range and flat, probably a good combination for your deer hunting. You don't need the extra pressure the .454 brings to the table, or the possibility of a sticking cartridge.
See Ross Seyfried and the .45 Colt killing a cape buffalo.
Heavy .45 Colt loads will do pretty much everything a .44 magnum will, and at lower pressure. Plus with the SRH you can load it with .454 if for some reason hogzilla moves in.
If you want a more powerful handgun, go up in caliber. The BFR in .500JRH
is pretty near perfect for a packing pistol. 440 grain bullets at 950 fps
are going to kill anything in the 48. If you are worried, you can run 420's at 1350 fps easily. Some have said these kill like a .375 H&H rifle.
.475 Linebaugh is no slouch, and ammunition can be found at reasonable prices now and then. These calibers are available in guns that are
packable, not the cannons that shoot the S&@ .500.
Grips:
Make sure that you get grips that fit YOUR hands. Your dabbling in a recoil area where if they are too small you aren't going to be able to shoot the gun. Never had grips that were too big, but I'm sure that would be a problem as well.
Best grip for me for heavy recoil, or at least up to 45 ft-lbs, is the FA 83, with the BFR with custom grips a close second. I find the Bisley grip gives
me a bit more to hold on to, but, with heavier recoil it hammers into the palm of my hand. The 'hump' in the grip really pounds my hand. On the other hand it just might be the recoil being at 65 ft-lbs, and no grip is going to soften that.
Once you get over about 275-300 grains and near full house loads grip
design becomes critical.
My .475 Linebaugh and .500 Linebaugh came with grips for a person with small hands. I had to grab the guns so hard for fear of getting killed by the recoil I couldn't shoot them accurately.