1950-62 235 manifolds bolt up exactly the same.
I suspect the alignment rings as I have experienced the same problem several times.
The problem comes in when an exhaust manifold has become warped up at each end over time(and most are). In many cases it is not possible to get the manifold started straight on the alignment rings with the two end studs in place.
I usually need to remove the end studs to install manifolds than I install bolts instead. A lot of times it is not possible to install anything in the end holes.
Do not try to pry down on the manifold once installed to get the end bolts in. That is a sure way to break the manifold.
