EGR manifold modifications

I have a question about modifying a stock egr intake manifold on a early 70's 350cid small block.

There is a small chamber that is right below where the air & fuel come into the manifold. This chamber is connected to the exhaust ports and the EGR. If the EGR was inplace the exhaust gasses in this chamber would flow through the egr and into the intake ports.

This is a circle track application and I am trying to milk every HP out of this motor. I am blocking off the egr, but I was wondering if I should also block off the entrances to this chamber? It seems that exhaust gasses in this chamber would heat up the incoming air and fuel mixture.

if anyone cares. i just talked to a guy at the machine shop. He told me to definitely block that chamber off.