has anyone used this?

Moparblood that is nothing more than a breakerless Mopar distributor mated to a GM 4 pin HEI. You can do all that yourself a LOT cheaper. Get yourself a slant breakerless distributor--came in 73 and later cars......and recurve it or have it recurved. There is a "limit plate" kit but I don't know if it works in slant distributors. Buy yourself a quality HEI module and hook it all up. Bypass the ballast resistor and you can even use your factory coil---at least for awhile

One of the great guys on here came up with this neat drawing of my "hen scratches"

4pin-jpg-jpg.jpg

BY THE WAY what are you working on as you neglected to mention. MAYBE you already have a breakerless distributor