If I was going to spend 50k on a motor I think I'd go for a Nelson Racing Engine Twin Turbo 454 LSX motor that came in at 1500 hp/tq on street gas (2500hp on race gas) for 52k:
http://www.nelsonracingengines.com/p..._454lsx_tt.pdf
Or I could save a bunch of cash and only get their street mannered model and settle for 900 hp/tq for only 28k:
http://www.nelsonracingengines.com/p..._402lsx_tt.pdf