I'll second Len's comment on reading Jays "Low buck 390 build". A good place to start to set some fundamentals.
BUT, 1st, If you want that kind of horsepower, first ditch the Performer intake. You'll need at least a Performer RPM. The Performer is for low end grunt and not suitable for higher horsepower.
2nd, you'll NEED headers, regardless of the drawbacks. Any factory exhaust, short of the long tube cast iron jobs, will kill your horsepower.
3rd, to reach those goals with a 390, you're gonna have to stroke it unless you want it to be on the VERY ragged edge, meaning not streetable. The popular 445 stroker would get you there and keep its ability to be street driven.