Have you done any porting before, or have you done any reading on the subject? just "hogging it out" isn't the way to approach this issue...
Understanding how air "flows" through the passages, much like water in a creek, is the key to knowing where and how much to modify. Air does not travel through it evenly from top to bottom or left to right, if it was, then "just make it bigger" is all you would need to do, and nobody would need a flow bench...
Start with the most constricted area.
Bowl porting is where you will make most of the difference. Enlarging the port openings isn't really necessary with this engine, especially for street use. Using the larger valves will only have a small effect at higher rpms.
There are two books out there by David Vizard that are about the SBC V8, but the info is useful for any engine.
"How to build max performance Chevy small blocks on a budget"
"How to build & modify Chevrolet small-block V-8 cylinder heads"
