They are very easy to install but I do not believe they are interchangable. I know they changed in 78 from the early 1000's but only slightly. I do not know for gospel but I really doubt a 77 will fit and 1100. Hopefully someone else will come along with a definitive answer.
What's wrong with the center stand that you need to change it out? Just follow the directions in the guides section and greas4e the pivot pin if it's tough or sticky. There's really not much to it. Only major issue is whether or not the Pivot Pin clears the exhaust. If it doesn't and you really want to fully remove the Pivot Pin then you have to drop the left side exhaust.
I'm busy this weekend and next, then have one weekend free this month. I'm always free mid week if you want to take a trip to western Wisconsin I can help you with it.
When I bought the 1100 I sold last year the center stand was bent like it had been hit, some one had heated it to get it to fit again but it did'nt fit right so I had a spare one off a 79 so what the heck put it on but the part that goes outside of muffler did'nt fit so I slipped a large pipe over that part of it did some bending and it worked great. Mel :waving: