Some additional $.02 here.
First, go to the local 7-11 magazine rack and pick up a copy of Street Rodder. They dyno tested a built up 390 FE punched out to 434 ci. See some of the parts they used.
You can get 500 hp out of a stroker 351, doing it with a bb shouldn't be a problem. Looking over the prices seems a little high, but not wildly high. Couple of things that I noticed though.
KB pistons. These are hypereutectic cast pistons. Don't get me wrong. They are a good street use mostly, and ocassional drag piston. They fit a lot tighter than forged pistons and maintain a better ring seal. For an engine that sees most of its life under 5500 RPM, they're very good. If you're going to race this motor, go with the forged pistons.
Solid roller cam. Typically, solid roller cams are race use, not street use cams. The roller lifters are not made for sustained highway driving. Crane Cams (the cam used in the SRM test engine) and Competition Cams make retrofit hydraulic roller cams for popular older motors not originally equipped with roller cams. Hydraulic rollers are awsome, and very streetable. Just don't go wild with the duration or you'll kill your bottom end. 224I/234E in a dual pattern cam is plenty. You can prolong valvespring life by getting them polymer coated with an
oil retentive coating. Keeps the springs wetted with
oil which helps keep them cool. When I sent my headers & sidepipes off to the coatings ship, I sent the valvesprings too. Different coating for different purpose.
There's a machine shop just off I95N, two exits North of the DC Beltway going towards Baltimore. Burtonsville Speed & Machine. Shop manager is Chuck. Knowlegeable bunch of guys, and a clean, professional looking shop.