With the stock rocker arms(1.35:1 ratio) it will be impossible to get anywhere near enough lift if you grind a stock cam. There isn't very much lobe to work with when you profile it for a roller lifter.
I had a stock cam ground for my 321" GMC and it had to be ground so the lobe base circle was clear down to the cam barrel. With the 1.85:1 roller rockers I built I got just over 0.600 lift at the valve with flat tappets. I needed that much lift so the engine would be able to use the intake flow at 0.600 lift.
Unless you have deep pockets or access to a "good" machine shop I'd suggest you build a 292.
Ron
