2bbl on single intake

I would make the effort to find a 2 barrel intake for the slant 6 so that you can use your 2 barrel carburetors ( I am assuming Carter BBD's). This ensures that the 2 barrel carburetor works as it is intended and there won't be a clearance problem. The factory super 6 set up works great, I think you are creating problems for yourself by trying to use an adapter.