Help with manifold

[landarts]

I purchased a 68 1/2 ton about a week ago and trying to get it running. The truck has sat for a long time with bad gas left in the tank and fuel system. I am working all items to be cleaned out or replaced to get it going. The motor is a 283 and had a rebuild on it about 30K ago. I knew that the carburetor would need to be removed and rebuilt. When I tried to remove the carburetor the two front stud mounts basically were rusted through and snapped of with the slightest pressure. The two back ones were fine and no signs of rust.

I proceeded to pull of the intake manifold so I could work on getting the rusted carburetor mounts out and the threads cleaned up. As I was working on it I remembered that I had two intake manifolds from 327 motors. When I flipped them over to compare I noticed that the 327 manifold had the middle most port blocked off and the manifold from the 283 had the middle port open.

Is it ok to use the 327 manifold with ports closed or do I need to stick with the 283 manifold and get the carburetor studs fixed.

Pict 1 is the broken off studs in the 283 manifold
Pict 2 is the two side by side for comparison
Pict 3 is the truck I bought