8point said "The 45-90 cartridge has piqued my interest as of late. I'm currently struggling with the desire to build a rifle that will shoot this cartridge."

The Miroku/Winchester 1886 45-90 TD handles 45-70 and 45-90 ammo just fine. Mine is very plain externally, but all standard internally.
[Linked Image from jpgbox.com]
From 300 grain light game loads to 450 grain DG loads at 2150 fps, it has proven to be an accurate and effective hunting rifle.

CRS, NRA Benefactor Life Member, Whittington Center, TSRA, DWWC, DRSS
Android Reloading Ballistics App at http://www.xplat.net/