Answering my own question and sharing some info:

Impco product updates:
http://www.impco.ws/product-updates.asp

Idle adjustment:
http://www.impco.ws/pdf/TSB-167.pdf

Impco ECU interface
http://www.impco.ws/spectrum-test-tools.asp

The taper plug on my carb is impossible to get to as it is right against the hydraulic valve block.

I don't think the Idle adjustment screw tis the proper approach to my problem because the high idle started instantly.

Yesterday I cleaned the crank sensor.
I am waiting for a Ecu interface cable. ($100) My Service shop some how does not have one.

I'm supposed to get a service manual today.