Mark,
If you check out the movie, he states is a 115 grain cartridge with a 540gr paper patch bullet. It's a straight walled case, so it only makes sense it's a .45-115.
The Shiloh rifles are great rifles, works of art! I think you can get a lower end plain Long Range Express for around $2k. Their wait time has gone down significantly, the last I heard. Otherwise there is C. Sharps, and Axtell, and a few other custom makers that make some VERY nice rifles.
Given I can't afford anything like that, I picked up a Pedersoli from Cabela's on sale for $1199 (now $1399). Picked up a Heilman Soule long range sight for about half of what MVA and other name brand sights go for, and it's a VERY good sight!
It's marked in MOA increments given a 36" sight radius.
The Pedersoli rear sight was sadly very lacking. Given the quality of the rifle, I was surprised they bothered to include such a crappy sight.
The front sight is not bad, but eventually, I'd like one with a built in level. Heilman makes a great one, again, for about half the cost of MVA stuff.
I might also cut a couple inches off of my barrel to try to get it down to legal weight for Silhouette. I'll have the opportunity to shoot more silhouette than long range, so I won't miss the extra barrel length.