We ground down the front of the TB and thermostat housing where they meet as much as I was comfortable doing but still didn't have enough room to use the gaskets.....went with a beed of RTV on either side of the plate, manifold/TB......did anyone else do this or were you able to grind away enough material to make the gaskets work?

 

You will be fine using the silicone. This is the down fall to putting a plate on a LT1. It is a very tite fit.
Dave