Rich Idle AFR reading

I will run through my set up real quick.

69 318 stock bottom end, 100k miles. Stock cam, timing chain etc.
Rebuilt heads (675s) comp springs 901s. Stock Lifters.
Weiand Stealth
Edelbrock 600 primary leaned out 2 jet sizes (.095) Rods and Secondary leaned out 1 size.
Hedman Long tube headers to 2 1/2 duals, no cross over, borla mufflers
Stock Box Mopar electronic ignition 12* initial and 34* all in at 2500 rpms.
Idle is set at 750 RPMs
It is a manual transmission.
I live at around 7k feet above Sea level.
AFR gauge is a wide band AEM on the even side collector.
Cruising numbers are 13-15:1 and mileage is way up to 13.
Idle after warm up is 11:1 off idle get right into 13:1
WOT is about 12:1, not really spending a lot of time there :)

After I finished putting every thing back together I used just the AFR gauge to set idle mixture to be about 14:1 on the gauge. It would go way to lean off idle and stumble, would go "---" at over 17+ AFR. So I pulled out the vacuum gauge and set the IMS to be highest vacuum, 14" on vacuum. That results in about a 11:1 AFR reading.

I am just learning and I know there is a lot of moving parts in getting this correct. So where should i look? I can lean out the IMS a little and sacrifice some vacuum. No power brakes so no problem there. But shouldn't highest vacuum be where the carb wants to idle. So is my rpm too low? Just lean it out and raise the rpm a little to see if the vacuum comes up? Or should I be looking at timing? At around 10* advanced I get some burbling on decel. So I bumped it to 12* and that went away.

Thanks for any help.