This work was done by Jim Murch. He employed a Trick Flow EFI manifold (upper and lower), the lower half has been modified to fit onto 351C 4V heads. The work required was extensive, much more extensive than modifying a tunnel ram. The manifold bolt holes of a 351W are all verticle, only the 4 center manifold bolts are verticle on a 351C. The 351W manifold bolt holes must be re-drilled to work on a 351C. The rear valley rail must be modified. Material had to be welded around the flanges for the larger 4V ports and then milled flat. Jim also spent time opening up the manifold runners to make them closer in size to the 4V ports. Jim's work looks absolutely first rate, the finished product doesn't look like a modified manifold, it looks like it was out-of-the-box.
Keep in mind, Trick Flow has developed a 351C 2V EFI manifold lower that makes all this work unecessary, its a direct bolt-on. And it mates with Trick Flows 351W EFI upper manifolds. Hopefully Trick Flow will make the flanges tall enough that the EFI lower will work with both 2V & 4V heads; this is what Edelbrock did with their new RPM Air Gap intake.
-G