Chevy C10 350 new Summit carb Question

[tobascofred]

Greetings all. I just purchased a Summit Racing M08600VS 600 CFM carb to replace a worn out Quadrajet, as well a 2969 Edlebrock adapter plate to go from the "square" carb bolt pattern to the 4 1/4 by 5 5/8 Quadrajet pattern on the intake manifold. (I think the carb is a direct copy of a Holley 1406 Performer).

The carb came with a very thick (thermal?) gasket (see photo). When I place that gasket on the adapter and site down the bores I see that it makes a really poor transition from carb bottom to adapter plate. I assume that this will mess up the air flow?

Does it make more sense to use a standard thin gasket (two supplied with adapter) for a cleaner transition or use the thick (thermal?) gasket? Thanks in advance for any insight.

tobascofred