[blue00gt]

Basically, if you are not planning on making the 1000+ hp that those internals support, then there is no reason to get them. Since your block and stock crank can hold up to alot of punishment, just get some decent forged rods and pistons and save yourself the cash and extra rotating mass.
Whether or not you need bigger injectors or a pump to support more fuel flow also depends on what your setup and power goals are going to be.
You need to set yourself up with a power goal you are trying meet and decide whether you are going to do it N/A, or with nitrous or forced induction. Then you can select your parts based around this stuff. Do you drive the car everyday? Do you roadrace it or drag race it?
If I were you I would just build the bottom end like I described and add a blower or turbo kit like Unit said and be done with it. Bolt-ons and headwork, etc. all add up fast as far as cost and aren't going to get you anywhere near the power level that forced induction will for the money. If you go with forced induction, you can enjoy all that power right away and still add the other parts later if you get bored with the kind of power you're making.
With the 4V motors it's pretty easy to get into the 400-600rwhp range with forced induction. You also need to keep in mind that if you plan on making big power then your stock clutch, tranny and rear end aren't going to hold up to it either.