600 starts to be a limit with the stock internals on a 2v 4.6 unless your talking about the 4v Cobra motor. The rods and crank just will not take it.
You can acheive 600hp on a 302 but be prepared to break the block in half. So if you want a nice, reliable motor with that kind of power your going to spend about $4200 on a 331 DART shortblock, $1500 in heads/springs, $600 in the intake, $800 in TB/MAF/INJ, $330 cam, $200-$500 in rockers, $750 in headers/x/cat back, $2500+ for the blower. Plus all the little things.... $10,000+
Then you need to do the chassis so the car doesn't twist up...