I'm not a cam afficionado or any cam guy. However for a street app. most don't go past 280 to maintain streetability. After all your not running at full throttle all the time. comp cams makes a pretty good listing of different styles of cam. even switching to one of those 280's would probly help you out.
That is of course provided you have eliminated all of the obvious first (carb, timing, fuel filter, wires, plugs, etc.).
My two cents