Can you weld? If you have enough skill to run a MiG, ( or have a good buddy who does) you can probably make a simple and effective log style manifold to mount any number of carbs. If you can do that you can certainly make a block off plate.
Personally, I believe the decidedly more simple motorcycle carb conversion, especially using the larger CV carb off an older Harley would be the easiest to fab and maintain. 1 carb to tune, simple manual cable actuated choke, CV operation for somewhat self adjusting fuel mixture once you get a good baseline setup, and can support up to 100hp, probably more. Tuning parts are readily available through the Harley aftermarket so any jet size or mounting adapter you needed is just a click away, or an HD dealer if you don't mind being raped in the wallet.
If you live somewhere HD parts aren't available, maybe another large CV off something else? You'll still have the ignition to deal with but it should be much easier, imo.