I just put a Pertronix in and used their own "Flame Thrower" coil which was only about 30 bucks and fits in the stock bracket (made in China though) . I do not recall a limited number of coils approved for their system but can check when I get home.

Haven't struck a match to the new engine so can't tell you how I like it, but I can tell you I chose it from my research and that it could be used in a stock distributor (looking stock from the exterior).