300 hp or more?

You can take your current block and make it a 4.2L/4.3L stroker, with a good enough cam and well ported heads and intakes, its a possibility to reach about 250-275rwhp on motor alone. Then add a minor shot of nitrous, and bingo! your 300 horses are at your door.

Do you plan on forging your bottom end? or you just doin a stock rebuild? Cam, head, and n2o will def get you there. I would recommend a 255 fuel pump and your lines will be fine. Im running stock lines and putting down low 500s to the wheels right now. As for injectors i believe 36lb injectors should be more than enough for you.
As far as power adder, turbo, sc, or n2o will all get you above 300hp. What about a m90 from the tbird. They can support 300hp. im sure you can find them cheap enough around you.