There would be absolutely no point to installing aftermarket rockers when you install a cam at the same time. Simply design the cam to exactly what you want with the 1.6 ratio rockers you have.
HP depends on the cam you choose. You could see as much as 30hp if you make it a really high duration cam, but it will not fit the heads, and you will end up hurting yourself at other areas in the RPM range.
Get the cam you want that will match the heads/intake/powerband that you want. Don't get one designed for your stock heads/intake.
If, for some strange reason, you wanted to do rockers + the cam, I imagine it would take your a better part of a day to do it, if it's your first time. There is a decent amount of stuff that needs to come off, and the first time is always the hardest.
Scott
There would be absolutely no point to installing aftermarket rockers when you install a cam at the same time. Simply design the cam to exactly what you want with the 1.6 ratio rockers you have.
I wouldn't say that at all. Roller rockers are made for a reason - they perform better than rocker arms.
I wouldn't use pedestal mount rockers for many reasons. Most importantly they're mickey mouse-ish. The pedestals can turn and twist, they can also lift and they've been known to "jump" when used on high lift short duration cams because of the valve speed and ramp rates of the cam.
Stud mount rockers, IMO, are the only way to go. In this case, you need to use an aftermarket rocker arm and a roller would be my only choice (I don't think they make rocker "arms" for stud mount SBF's).