I think you are near Orlando? I had LaMotta Performance do my driveshaft and gear swap. He does lots of Mustang work. Or call MPT to see who they recommend in the area. I am in the Tampa area and had my diff replaced locally.
The intake was designed for boost. The design would not be good for naturally aspirated engines at all. He never made any more of them and doubt he would at this point. The best option is to get the stock manifolds ported.