Sorry, but the FatCat (as much as I love them) is NOT gonna be a good pipe for a hot 120.
A motor that flirts with 130 HP has to breath & while the FC rocks on smaller motors & even some "torque-centric" bigger motors, it just won't flow enough for something like this mystery 120R.
Better be look'n for a Boarzilla.
As far as the motor goes, I sure wouldn't be lined up for any of the 1st ones. Let someone else find the shortcomings (crank, crank bearings, cam, etc) & you'll significantly improve your chances of satisfaction....
Additionally, building a motor for some ridiculous HP "#'s" does not bode too well for what the typical Bagger Dude is after ~ TORQUE. I know that it's gonna have decent torque, but it sure looks like the focus is more on higher RPM power, than low ~ midrange.
But then, WTF do I know.....