For a single barrel carburetor, the stock 235 intake design is about as good as you can get for normal operation on an unmodified engine.
The intake is heated underneath by passages from the exhaust manifold. There is an isolator that goes between the intake and the carburetor base.
I would try to use as much of the original intake, as designed, as possible.

I think Jerry gave you an excellent recommendation in a previous posting (relocating the studs):
https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1374608/2.html

I copied the attached intake picture but I failed to note the owner. The top of the intake was cut to study the possibility of adding a 2GC.
Note the heat passages and the cast iron material around it.

The top of the intake manifold must be flat. The isolator sits on top with no gasket. You want perfection here so there are no air leaks (will drive the EFI and carburetor nuts).
There is a gasket between the isolator and carburetor so I assume one would be needed for the EFI.
Attachments
235 Intake.jpg (80.24 KB, 442 downloads)

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."