you posted while i was typing...

650 out of your ls isn't going to be that hard to get... you might need a touch more than the 20-25 you were talking about earlier, but fully built, you ought to be fine.
for your fuel questions, hit up google and do a search for injector size calculator. you ought to find a site that explains all it. there is actually a right injector size for every set up, and it isn't just bigger is better.
make sure that the rest of your build can handle your power goals. you're gonna want to get head work done. a forged bottom end, that can handle higher rpms.
forged, balanced, fueled, and tuned, and you ought to have the power you are looking for.