That is an L67 lower intake manifold with the inlet mostly welded up. The big block with the round hole and 3 bolts sticking out of it is the LS1 throttle body adaptor. He is going to be bolting the LS1 tb to that so instead of the tb facing sideways like all other setup's it is facing up.

The coolant holes and PCV etc is all blocked off and he is doing a catch can for PCV I believe.

I'll let Corey give you the exact details but that is the gist of it.