It sounds like the LD works. I mean, there probably aren't many small blocks out there with that particular intake making anywhere near 523 HP. As I understand it, intakes with small runners increase the velocity of the A/F mixture going through the intake tract which translates into more torque. Not sure what an AG would gain you, maybe a few HP? It is fun to swap parts though, can't hurt to give it a shot.
Have you tried a different carb to see if the symptoms are the same? Not something random but a known good running carb. Might be worth a try, easy enough to do.
Or, take a big swing at something and adjust a parameter to the edge of spec to see if it has an effect one way or another.
Sorry if I missed it but do you have an A/F gauge hooked up? They can help make the tuning process go quicker.
