The single gear cam will service only the A10 & the 1200 engine, while the two gear cam was intended for the Later A12 & larger engines. I believe that you can also use it in the A10 & 1200 engine if you cover the fuel pump hole in these earlier engines & run an electric pump.

I may well be interested in the single gear cam if uterous can't use it. I will contact you by e-mail.

Edit
Oops, you have no e-mail, so check your PM