Lucky Me, Now What

I'd do more homework. IMO, you wont get 500hp from a 426" engine with that cam. The best choice, if you want a B wedge stroker, is one of those 400 blocks that's hanging around, either a welded and offset ground 440 crank to get 3.915, or better yet, the 440 Source rotating kit (making 470"), and a set of cleaned up RPMs on it. That will give you huge torque, good quench, take weight off the nose, and with the right cam (yes, your choice is too small) will make 500hp and more importantly, 500+ torque.