Roller Cam Question


I've been through a lot of older threads regarding roller cams and I still have questions.

I know I am going with a roller cam. The grind I can figure out myself, I believe. However, when picking a roller cam, what determining factors would make me go with a billet over the austemper roller cams. Also what mods would need to be completed to the block/timing cover for the billet/austemper rollers? Thanks.
No mods for the Austemper like Full Throttle sells. Never installed a billet but its a different setup with more work involved. I know shims are needed for a start. Not a lot more than that I know about them come install time.
Billet core cams do not have an oiling provision for the cam sensor gear. Cast cams like the XR series do have an oiling hole.