Ted -
I wrote a similar response to
another post recently.
I don't use gaskets with the insulator on my '54 3100 235. I have no leaks. Gaskets raised the heigth of my carb thus making the accelerator rod to the carb too short. The throttle butterfly would not open fully.
The insulator and carb rod are originals that I purchased from forum members. It's possible that they are from a different year 235, or that accelerator rod assembly bellcrank is worn, but bottom line - everything works.