Billy Briggs Racing engines. He is very well known and reputable, just finished up this LSX for Pro-stock motorcycle rider Eddie Krawick. He's up in Michigan, but is the best and you won't be disappointed. Do a google search on him if you are leary.
If you are set on a pro-charger Steve Morris race engines is the place to go to. He works hand in hand with Procharger doing R&D work and recently released the Provolute which has had some serious gains in HP just by bolting it on to the inlet. He has a website and its...he is also a top notch builder
http://www.stevemorrisengines.com/