'80 242GT 92k miles, M46

I hope you guys with the B230F/T engines realize how lucky you are with regards to throttle body cleaning! I won't go into descriptive detail of what a PITA job it was...anyone who has the B21F can likely commiserate with me and hopefully offer some advice on making the job a little easier. Glad I did the job (TB was filthy, gasket brittle) but now I have a constant high idle which sits at around 2300rpm.

I've searched the 700/900 FAQ and read my Bentley manual but am still confused. The Bentley offers instructions for the '83+ CIS system which apparently has a throttle switch, my '80 doesn't appear to have this throttle switch. The closest idle adjustment description is in the 700/900 FAQ: Throttle Body Cleaned, Idle too High which sounds like the right fix for my TB but have some doubts since it's for 700/900 series cars. Did the 700/900s ever have the B21F?

My questions:
1) With my constant high idle running at ~2300rpm, what is the correct sequence to follow to tune it down? My first step is to search for vacuum leaks (visual check shows air boot in proper position).

2) Would like to buy a "tuning" tachometer for adjusting idle rpm. Any good sources?

Thanks!
Bean
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'80 242GT 91k, '94 945T 110k