Can you guess my cam?

Joe's car sounds spot on to what I remember the .508" being like thru mufflers at a idle speed in the 1000/1100 range. Your at 24*, so that may let you idle at the lower rpm? The vacuum number @3000 really doesn't mean much, other then it tells me the "manifold" vac is probably in the mid/high single digits at idle.

Honestly, we're all grasping at straws here. I think your in the [email protected] plus range. If it is indeed a .508" that was dialed in right, it will be soft down low without at least a 3.91 gear and will really be in the sweet spot from 3500 r's up.