If interested in more details on fitment issues, some great info from Kelly Coffield's work on EFI as shared by Dan Jones here: https://pantera.infopop.cc/topic/351c-crossram-efi
I have one of Kelly's intakes and it's well designed but it's made for a 9.5" tall block and C302B or Brodix heads. He also had a version for 9.2" blocks with the same heads. Kelly's throttle bodies are "low profile" so the system, with air cleaners, will all fit below the rear deck lid. I made some modifications to mine, to lift the TB's about 3" and aim the injectors at the intake valve. This gives me an effectively longer runner but still (barely) fits below the deck lid. I'm using a Holley Dominator ECU and Jenvey drive-by-wire.
Not only did Morrison tell me it would take a year or more (possibly much more) to manufacture an intake for me, they wanted 50% up front...non-refundable! I suggested putting funds in trust or a "ship-by or provide a refund" deadline but they would have none of it!
It seems to me, for a 351C, the only readily available IR intake manifold is Hall's. Hilborn and Kinsler have intake systems with the manifold and throttle bodies integrated. They are both great companies and their stuff is awesome but their markets are more race than street. That being said, I seem to see lots of their stuff on street cars; mostly high end hot rods. If you don't mind going overseas, there are the Redline and Aussie Speed manifolds but I'm not sure of availability.