A cam with the duration in the neighborhood of 210-220 @ .050 lift is a pretty good daily driver cam. Anything larger will lower your vacuum signal and affect idle quality.

I use 214/224 cams (dual pattern cams) in my mild build 302s and 351s. There is said to be a gain in power by using the 351W cam in 302s (using the 351W firing order of course) but I think the only real noticable gains are in the higher performance apps.

Your best gains would be switching to aftermarket heads or hogging the crap out of your stock heads and installing bigger valves. Anymore the aftermarket heads are cheaper that modifying the stockers.