I'm mating the US250 to a Crossflow head. I haven't obtained the block yet, but when I do, I'll probably need to have the bottom end rebuilt. I'll probably get a slight overbore and have the deck milled. I'll be gathering up the valvetrain components over the next few weeks. I'm not sure yet whether I'll do the valvetrain assembly myself, or hand everything over to the shop and have them get the engine up to running condition. It depends on how much time I have. I'm definitely doing the intake, exhaust, ignition and fuel delivery myself.
I haven't personally checked out any shops at all yet. I plan on asking around at Ford Carlisle when I get together with the Keystone Chapter of the Falcon Club.