I went through and made sure every header bolt was torqued, nothing had loosened and there was no evidence of a leak at the heads. I think the issue is at the collectors, and it directs the noise towards the front of the car. I crawled under while the engine was running and there is no leak anywhere near the cutouts. There is no room for a clamp, short of me removing the collectors, slotting each primary tube and welding on draw tabs. I may try the permatex method and hope it doesn't blow out.
I did find the main culprit for the exhaust stench. The hood scoop blinker harness had pulled forward (CVF hinges open higher, so I needed a larger strain relief) and the grommets were no longer sealed up by the cowl. That was an easy fix. Every other area was sealed properly on the firewall and under the car.
Overall it is running great and I have worked out every other major issue. Drives are getting more enjoyable and less nerve-wracking.