Tunnel Ram Tune

Hey folks, just going to throw this out there. Posted on a different forum and thought why not here too.

I'm looking for some direction in a lean condition at cruise. I suspect it is related to the transition between the end of the transition slots and the beginning of the mains coming on. I can feel and hear the engine going lean and flat in the cruise range of 50-60mph.
MPH RPM AFR
35 1500 14
45 1900 15.5
55 2250 16.5-17
65 2800 15
70 3050 14.5
It runs and feels good in the 14-15 afr cruise range.

The car/engine specs:
440 Dodge, 10.0 CR, iron 915 closed chamber heads with chambers cleaned up and mild porting. 231/237 @ .050 110 lobe separation 106 ICL, Weiand 1987 Hi-Ram Tunnel Ram w/2 ProForm 750 DP, 3000 stall and 3.23 gears.
It runs really well and am very happy with it overall. Its just that lean area that bothers me at this point, it just sound and feels "off" there. I'll throw in that the timing is 19* at idle and has a fast curve, all in by 2300 rpm. I am running vacuum advance (ported at this time). I've tested with the vac can disconnected thinking maybe there was too much timing at those cruise speeds but the change (if any) was really unnoticeable. I have the secondaries wired closed as I am working on the cruise and PV circuit at this point. I will note that this is a 100% street driven car that occasionally gets a little romp on back country roads.
The carbs:
Primary Secondary
.031 IFR .031
.078 IAB .078
.085 TSR .080
.046 PVRC ---
.036 MAB .036
#74 MainJet #80

I'll have the carbs apart this weekend to change PV's from 10.5 to 8.5 i believe the PV's are coming in a tic early (unrelated issue) so any suggestions are welcomed and appreciated.