You can flash anything that uses [GEE] sources, so anything from international OR Sprint that says [GEE] will work as long as you flash a [GEEB] kernel afterward.
However, if it says [LS970] or [FL180], those roms wont work. Look for [GEE] and you'll be good.
Main: HTC One M8 - InsertCoin
Traded: LG Optimus G E970, 4.1.2
Loaned: HTC Inspire 4g, PACMAN
Auxiliary: HTC Incredible, tinyCM10.1
Auxiliary: Nook Color, MirageCM7