Isn't a Weiand 8007 a small port manifold? I thought it was comparable to an Edelbrock LD4B, and Weiand had another dual plane that was more comparable to an LD340.
72 340's used J heads, not small port. Smaller 1.88 intake valves are the only difference. You will see a power loss when you swap out that intake and the 72 340 TQ.