Don't horsepower shop. Shop for reliability. These are just the BASICS - and yes since you're hunting big power I say that sleeves are part of the basics.

* sleeves
* forged internals (rods/pistons) - Scat makes the lightest rods (out of the box) for a B series. And you want around 12:0 CR (any more and we get into splitting the flame front which is beyond the scope of this thread)
*gaskets/bearings
* bolts ons (IM, KiddRacing header, flywheel, exhaust)

That is just "basic" stuff. What's gonna set you apart from the rest is the top end. If you don't want a $1000 - $2000 head then no point in doing none of the above really. The head is what brings home the bacon.

http://www.stewartengines.com/ or www.team4piston.com is a good place to start.

Build this motor on paper - call around, get prices for assembly (MSS Racing, MSP, etc) and parts. If your pockets still don't get nervous go for it. You don't have to make 300hp to outrun a lot of local FR guys. Good luck.