The Miura is one of my all time favorite cars. I have a bunch of photos I took of various design details that I love about it. Even on the stock version, those side scoops are terrific. I think they could be incorporated into the X's stock B-pillar/targa bar.
I posted a bunch of different side scoops styles I like from other great car designs in the referenced "design" thread. Many of them are located down lower on the side panels, especially on more modern models, but some are up on the pillar. However those typically have long rearward extending pillars, with more panel space for a big scoop running horizontally. For the X I'd prefer to keep it shorter and have the scoops more vertical.
If you built a lengthened rear extension for the X's B-pillar ("fastback" look), how about a clear cover in between them over the engine? I have some good examples of that on various supercars...great look.