I bought an Indy 400 manifold from Andy that I plan to make some spacers to adapt to my 440 block. The spacers will block off the notches on the 286 MW intake faces. I'm going to order one of the 337 intakes and dyno test both and see how they compare. I also bought a TM-7 that was welded up for MW ports and has a flat plate welded to the bottom to try as well. The 337 looks like the easy way to go, and from Andy's testing, looks like a good piece.