If you're going to buy a rifle chambered in 5 dollar bills, buy an appropriate scope or you'll be wasting your money.
Do you need FFP? Depends. FFP is good because if you have to take a shot at multiple distances, you can hold at different points on your mil reticle at any magnification, and it will hit where you point.
On a SFP scope, the mil scale is only accurate at full magnification. With a 15x scope, this isn't so much of a problem. With a 22-25x, you pretty much need FFP because you'll want to dial down due to mirage.
on the other hand if you click in your adjustments and don't use the mil scale on your crosshair, SFP is cheaper than FFP.
At minimum I would get the nightforce 15x F1, fantastic scope for the money. But you might want a little more magnification, so any of the 25x FFP scopes (S&B PMII, Premier or NF would be fine)
The NF Beast is supposed to be a great scope, but I don't think it has hit the streets yet.
If you're on a budget, get the SFP NXS nightforce and just click in your elevation.
Don't skimp on rings either, I like American Rifle Company rings and NF rings, but badger, seekins, etc work just as well.