Need tuning help on 340

Lunati at the time said 1800-5800 and I installed at their recommended advance.

But as I said, the motor has always happily revved way past that. Has seen 7,000 many times, but I usually shift at 6200-6500. I don't run at the strip but a few times a year, so am no expert at any of this. It just started feeling dead at the top end as I've gotten the A/F #'s "where they told me they should be" and unless I'm missing something the motor apparently does not agree.

I'm heading out now to have a good shop put their timing light on it to see if mine is off. And I am not sure how to check if I'm getting enough fuel pressure at the top end. Maybe I do need to rejet back to richer mix.