A Turnbull custom Marlin in .50 Alaskan would also be a good choice.

The model 1876's by Uberti are about the best of the 76 repros, but the .50/95 is the longest case they can feed and chamber.
An 86 is needed for a 2.1" case - or the 2.4" if wanted.

My Bro has the Pedersoli model 86/71 in .45/70 - a Beautifully smooth action and pistol grip of the model 71 Winchesters that came out in .348.

He also has a Browning (Miroku) Win. 86 in .45/70 (much more expensive than the Pedersoli), but had to re-stock it - wonderful job, of course due to not relishing the recoil - lol.

Until he restocked the Browning with in fancy walnut shotgun butt all beautifully finished and checkered, the Pedersoli was a MUCH nicer rifle.

The Pedersoli action is still smoother, the pistol grip and fancy walnut is especially nice too. A re-barrel to .50 could be done fairly easily I think and re-chamber to .50 Alaskan as the rims of the parent .348 case and the .45/70 are the same size- so no action work, I think.

What work would be needed for the larger .50/110, I do not know. Dave Scovil (Rifle/Handloader Editor)had a Model 86 in .50/110(I think it was) re-barreled with a faster twist barrel and chambered for the .50/110/450 ctg. by Turnbull.
With that, he shot a bunch of African game including croc, I think, along with a hippo.

The cheaper route, the Marlin model 1895 converted to .50 Alaskan will handle loads listed in the May 2012 magazine page 56. Really good article by Brian Pearce.
Best loads--435gr. 2,118fps
-------------530gr. 1,908fps
-------------680gr. 1,581fps
-------------450gr. 1,911fps Barnes Original SP
-------------460gr. 1,916fps for the jacketed solid

There are a few factory loads now as well.
400gr. FP bonded core - 2,153fps
450gr. LFN G/C--------- 2,112fps
450gr. Bonded JFN------ 2,059fps
460gr. Punch Solid----- 1,917fps
500gr. JFN ------------ 1,866fps
525gr. Buffalo WFN-G/C- 1,863fps
525gr/ Grizzly WFN-G/C- 1,847fps

The best I did with 420gr. from my .50/95 was 1,845fps. I felt I could go higher, but didn't. The .50/95 is a larger case than the .50 Alaskan, being the same as the .50/110, except for being shorter, my case being only 1.9" - made by Jamison or made from .50/90 Sharps cases,which I assume the .50/110's are as well.

I mentioned Turnbull - here's another Grizzly Custom who also produces the ammo, I assume.

http://www.grizzlycustom.com/