how much cam before studs and roller rockers?

So in the real world, how much cam can you run without getting into the machine for studs/guideplates option?
the 280h? Im just looking to push the power band up to 1500-6000 rpm.. not crazy but a mild street cam with a bit of a lope.

I understand that as the lift goes up the cam is actually smaller in diameter and that means longer push rods and or shimming the pedestals, which is no problem. what I dont know is how far you can go without getting into trouble.
Comp cams 280h recommends a .150 longer pushrod but also machining for studs and guide plates which could be .75 of that?