Until the engine is idling on its own, the BAC is going to complicate things. If the engine doesn't have a stable idle the BAC will chase the instability. It's best to start at the basics. Get the engine idling reasonably well and recovering from idle variations. Generally this means making the idle area of the fuel and timing map look like a valley. The idle bin should be the center of the valley with slightly richer and more timing surrounding it. Will tend to make the idle self-correcting.

Then start tuning the BAC.

Yep, 18 degrees of timing is a lot of timing at idle. Mainly done to give people some hope of ending up with a running car. The idea being that they would then adjust their timing to the specific situation.

Once you have a fairly decent tune you should be able to go rather leaner than 12.6 by adjusting injector angle and after the seals have broken in. The RA Super Seals take thousands of KM to break in. You will notice continual improvements in vacuum during this, probably necessitating map adjustments.