We can debate this forever. I think if you already have SUs, keep them. Depending upon how the conversion was done, you may have a lot of parts to source. Expensive little parts that are diminishing in supply. You can't really make the statement that 'SUs give you HP' usless you are unimformed (or 12 yrs old). Many factors are involved there.

well i would be running a stage 3 cam and a MSA header. would SU's or EFI be better (say if i had larger injectors and a 240sx throttle body.)

Stage 3 sounds like a lot of cam for EFI, maybe even too much for SUs. I'd ask the cam grinder what they recommend for use with that cam.

Keep the round tops, and for a cheap cam, try the 260 stock cam. check the numbers, it's a tad bit hotter.