There are the Vortec kits guys convert to fit. I believe this requires fabbing or modding the mounting plates and tubing. Ask around at 332-428 Ford FE Engine Forum Few guys there are into them and can help you out. Look for Jay Brown there he runs one on his 511" aluminum Shelby engine. Good luck.
Just to add.....on the Cobra Automotive site click on "Horsepower" under the site header. This will bring you to the page with the Paxton setup. FWIW these guys are VERY good at what they do. They are local to me.