Going to a "bigger" cam will reduce the need for high octane, not increase it. A cam with about 215/225 degrees duration @ .050" and about .450" lift and 110 to 112 LCA works very well in a street driven Pontiac 400 with an automatic. I've had good results with Comp and Crower.
Check through this list of Pontiac cams and you'll see that there are a few options. The factory cams have a wider LCA and shorter lift than the aftermarket cams.
