The referenced link shows an "almost correct" gasket (what should be in the kit), an incorrect gasket, and an aftermarket "fits all" that may be used.

235 mounting gaskets

The original gasket was affixed to a 1/2 inch heat insulator (VERY expensive to reproduce). The
"almost correct" (it is correct except for thickness) gasket should be used WITH the original heat insulator (the insulator sits on the manifold, with the gasket between the insulator and the carburetor).

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop