G'day Fozzy
My experience is that when heads are machined to suit roller rocker studs.
Material is removed from the heads to enable the fitting of the studs and keep the rocker angles realistic.
You will not be able to run stock (stamped) rockers with these modified heads unless there is a conversion I don't know about.
If you are running a mild cam will you really need taller covers?

I'm in Australia, we didn't have the same AC setup here and had Clevelands as factory.

Hope this helps

Mike