most people generally go to FTI, Cam Innovations, Comp Cams, and a bunch of others, the best two would be between:
FlowtechInductions~ Ed
&
CamInnovations ~ Jay
i spoke with a guy at comp cams for about a week before I went and did it. Told him what I had, and what i was looking for. A had a great combo with an off the shelf cam... Totally different beast.. i wish I had done it a LONG LONG time ago