Any Buick V-6, self-contained ESC system would be fine - such as below. I think these were used from 1978 through 1983-ish on turbo engines... Not sure if the pickup coil in the HEI distributor is ESC-specific. I know that some later ESC systems are integrated with the ECU, that would not be good for my purpose...
Self contained were 78 to 80 only. I've got everything you need, but it wasn't cheap when I bought it. I'm guessing here, but you're setting up a draw through set up?