Well I thought I’d follow up on this thread since I finally solved the issue. If you recall I’ve had a pretty rough idle with a hot engine ever since I’ve owned the car (4 years). If you read above you can see everything I tried. I also switched to UO needles this summer - didn’t solve the problem but they really woke up the engine. Performance is better than ever.
I was suspicious that the rear carb was running rich so I decided to set the float from that carb about 1/8” lower than spec. Problem solved. I now have a smooth idle between 700-800 rpm. If anyone knows why this worked I’m interested to hear. Thanks.