Help Exhaust manifold compatibility

[81J10]

I've got a 91 4.6 stroker that I am going to add Mopar (hesco) MPI to, Hesco recommended that I use a set of later model cast iron exhaust manifolds, so
I bought a set. I just bought a 91 gasket and I was going to do some porting to match, but it doesn't look like the gasket lines up with the manifold. (hesco say's no problem). Hoping someone has experience with this and can let me know. I had planned to do a little porting ,ceramic coat ,then run duals. Any help
is apppreciated. Thanks in advance