I bought the exact same one. Same vendor. LOVE it! Made good dyno HP.
However, the one I got was equipped w/a hardened gear. I couldn't scratch it w/a new bit in my drill press. Since I have new cam, I had to buy MSD part# 8005, an IRON gear, for $50. From what I understand, and was advised by the guys I trust here, this gear would have chewed my new cams' softer gear right up..post haste.
You can search the forum for "HEI install". You'll find some good info. Like what has to be removed to make this work best.
Now if you are using your old cam, take the gear off your old dizzy, and pop it on this unit & you'll be set!
Good luck, and let us know what YOU think of it and how it performs.
I've also learned that sometimes... when people don't agree with you .... its best to hold them down and kidney punch them till they agree with you