My 1980 Rabbit which had a points distributor and CIS basic never had any "ECU". Not a hard thing to do. For many years I always said that the radio was the "smartest" component on the entire car. Now it is on MS and runs as good as it ever has.
As for what ign you can use, a system from an '81 will be the "breakerless" dizzy and will work. I had a "Cali" car from the 1980 model year that also had the same ign, but I think it was made "50 state" in '81.