If I was going to make a simple universal part with multiple applications, I would look at a 235/261 (big port) intake stub: a flange with ears like stock and a tube with the port ID 4-5" long with an open end.
3 of them makes a log manifold by terminating in a 2" or larger cylinder running across.
It could be an IR, each tube could end in an S.U. flange, a Carter YH, Mikuni, KeiHin, etc. stub depending on the carburetor's mount.
Since the only force is vacuum, epoxy may be sufficient to assembly.
Add a tab here & there for throttle linkage, fuel manifold, choke, etc.
