I use an Aspencade 1983 GL1100AD myself and have fitted cams from a 1975 GL1000. They fit straight in BUT if you are using the standard ignition setup you will have to remove the end off the left hand cam ( that holds the auto-advance unit on the 1000 ) or do what I did and fit the ignition unit in its entirety from the 1000 engine , which bolts on the end of the head where the 1100 has a chrome cover. I had to fiddle a little with the ignition timing , retarded it a couple of degrees , in order to make the bike run properly. The bike shows an increase in pulling power during the midrange , where I needed it most. Have no real idea if there is a real increase in top speed as I have NO interest in outright performance.