Ok, what kind of miles are on the engine......more than 100k? If it were mine and the compression was down on a few cylinders, or it's using oil, I'd go ahead and freshen it up.
The kind of power your looking at, all of the stock components will work. I used a stock crank (shot peened and chamfered) on my last setup and it made 500hp with a set of aftermarket rods and pistons. If it's all prepped right, it will last.
If moneys tight, and it will be after you start buying parts to go with the blower, just give it a ring and bearing job. Addtionally you can have the rods reconditioned with a larger rod bolt and have the crank turned or polished. Again, the money available will dictate what you do.
As far as your blower kit is concerned, does it come with everything?( fuel pump, fmu, wiring, etc) If an FMU is used, you can get buy without a larger injector, but a some point in time I'd upgrade to a larger set with a matching MAF and ditch the FMU. An aftermarket intake will always help, as will a larger TB and EGR.
On a side note, I'm not sure what kit your pricing, or which model it is, but it seems a little on the high side. My buddy just bought a Vortech SQ for 2700 to his door. It's pretty damn quiet, and in my opinion, an much better blower for the money. Just my 2 cents
