Rich Idle AFR reading

Make sure that your fuel level is correct. Then
Get your T-port sync dialed in, then
leave your speed screw alone.Then
Adjust your idle speed with timing and idle-air bypass and nothing else.
Your combo should not need any idle-air bypass.

The mixture screws are to fine-tune the idle quality. Forget trying to tune the idle with the AFR gauge.
If the mixture screws cannot get the quality of idle that you expect with the screws in the center or near center point of their adjustment..... THEN you can adjust the speed screw up to 1/2 turn, whichever way it needs to go as revealed by where the mixture screws are, and then reset the mixture screws to their centerpoint +/-, 1/2 turn. This is not an idle speed adjustment now!! This is a transfer fuel adjustment to get the mixture screws in the zone.
Idle speed is still adjusted with timing and idle-air bypass and nothing else,as above.
With a manual trans, don't be afraid to idle it up near 700/750. By the same token, try not to run more than 16/18 initial. I'm too lazy to go search what cam you are running but the 14" idle tells me it's pretty tame, and so it doesn't need a lot of initial timing. Run the minimum amount to get your target idle timing with the T-port sync correctly set.
Don't forget to limit the full-load timing to 35ish; whatever it takes to keep it out of detonation. At 7000 ft,you may have to delay full timing to a higher than usual rpm.

But before you do anything check that your jets( all of them)are still screwed down and that the metering rods are undamaged and properly located. Take the springs right out, to set the lowspeed running ...if you have to