Pre-68 Dave is the man for questions like that. I know he's mentioned successfully using a 216 manifold/carb on a "modern" 235. I think DADS50 might also run a 216 manifold on a 235.
First off, need to confirm port size. I think Jerry is right about the smaller ports on a dipper 235, but not certain. Either way, if you have the original carb for the 46 235, you already have the advantage of a properly designed CFM for the displacement.
I think I would adapt the original manifold rather than trying to drill and tap the casting for vacuum hookup, but others might chime in with a different opinion.
