I don't know that I'd lower a 1600 Classic. At least not very much. You don't have much lean angle available to start with, and lowering the bike will restrict leaning even more.
Having said that... Changing the shocks on a 1600 is a simple, straight-forward task. If you're at all handy, you should have no problem doing it at home.
A bike lift will definitely come in handy. Remove the mounting nuts at top and bottom of the old shocks. Raise the bike just enough to unload the shocks completely, then remove them. Place the top mounting eye of one new shock on the mount post, then lower the bike on the lift VERY SLOWLY until the bottom mount lines up. Put the bottom mount in place, then replace the nuts, washers, and whatever else. Then do the other shock, while you have the bike at that perfect height. Let the bike down all the way then torque the nuts down properly. Now go for a ride. 8)