Originally Posted By: panic
Looks like they bolt on. There may be enough room to cut the flanged entry out of the bottom of the plenum. Make it 5/16" longer on the farther end, and reverse it, then weld. This will move the actual opening and the flange for the runner by the pitch distance difference (8mm).

The linkage should be examined: what is it now, and what do you want it to be?
No personal experience, but I would not try to run the engine on the center (#3) carburetor alone - that #3-4 port will drink all of it.
The most likely choice for race is all 5 in synch (all levers attach at the same length from the throttle shaft).
The street choice with progressive (staged) linkage is probably #2 & 4 for primary to attempt (!!) some mixture distribution. The progressive part will look very similar to any other progressive, even V8, as to how to calculate lever lengths. I have some more text on this here: http://victorylibrary.com/mopar/log-2.htm


I'm hoping/wanting to leave the main body alone. I don't want to put too much heat in there and warp it. I was considering turning blanks and block all the holes up, and move everything over to suit the port spacing on the GMC, and buying new 90 elbows from Patrick from the new repo Howard manifold. I shall take a closer look at what meat is on the bottom of the body/plenum.

As for linkage set up, the car isn't a street car, our UK rags make it hard to build a car from parts and register it. Strictly event use, which by the sounds of it makes this a bit easy for carb set up.