Flat cams go on 206, 306 and a few other's, cams that look like a tophat go on later machines.
I have a 306 and the first 10 of the 30 or so cams made for it.
AshleyR has a recent thread on a 206 (that I should go and buy from her while I am in the neighborhood) with some nice pictures, and I have pictures of my 306 in my albums, you can see them from my profile page.