That 200ci was Chevy's first V6. It was only used 1978-79 in 49-state Chevrolets (maybe some Pontiacs). It shares most things with the 267ci V8, which was also only used a few years. The problem was the square bore/stroke ratio, leaving very small valves. Not very powerful, and not much better economy than the 305 V8. In 1980 the 200 was replaced with the 229ci V6, which had the same bore stroke as the 305. I think 1980 was also the last year for the 267 V8.
You can get everything to rebuild it stock, but performance parts are slim. Pretty much limited to what will swap over from the 4.3L V6 (intake, carbs, exhaust), and most of that stuff won't be useful on a very small engine like the 200.