Holley Idle Screws Not Responsive

The initial timing is 12 degrees and at 2600 rpm its 28 degrees. Any more timing and it starts to ping. I think my Mopar electronic distributor vacuum advance is getting a bit weak. Its a 9.5 compression 340/416 with a xe274h Comp Cam.

Can I check the throttle plate position in comparison to the transfer slots from the top of the carb?