if it helps the budget there's a 460 posted in the parts section for $150.
it may be easy to build up but the 400 hp is easy to get to. the heads make the engine in the case of 460s. they need to breath. if you go with the stock 2.02 heads use stainless valves and 292 In 300 ex with about a .560 lift at the lobe. the best cam is the stock cobra jet cams with the hydraulic lifters(about .490 lift at the lobe). the stock super cobra cam is a solid unit and a pain to keep adjusted in. the com cams folks make a few nice cams for high torque if you want good low end.