W123 280

[PILOT MAN]

My 1983 280 W123 Has No Tach, I Have An Tach From A Similar Model (280e) I Now Want To Remove The Large Watch From My Cluster And Install The Tach. The Tach Has A Plug At The Back For Two Wires, Where Does This Wires Connect.
I Suppose One Is A Ground And The Other Connects To The (-) Side Of The Coil. If I Connect Like This Would It Work?

I Also Have The Solex Carb On My W123, And Cold Starts Is Terrible, But Once Warmed Up It Is Perfect, And The C.o. Is 2.0% When Warm, Ti Just Fitted A Repair Kit To The Carb, And Cleaned It Good. The Choke Flap On The Primary Side Is Closed When Cold, But Can Be Pressed Open With Minimal Force, I Think Something Is Not Connected Correctly On The Choke Assembly On The Side Of The Carb. I Have 12v On The Choke Element.

What Can Cause This Hard Syarting When Cold