What to do first?

When you claim "rich", presumably you see black smoke from the exhaust and a loss of power. If lean, you will also lose power but the engine will miss and stutter. As mentioned, the most likely cause is the choke plate isn't opening. That is at the very top of the carb so easy to see and diagnose (true in all 1970's engines, even if not a slant or even a Mopar). 2nd most likely is that the float isn't closing to maintain the fuel level in the carburetor bowl. The excess overflows into the throat. That can be a problem will all carburetors.

BTW, what is "a computer for ignition"? The only one I have heard of that does just spark is MegaJolt from the megasquirt site.