Welcome, great bike and even better find.. I've picked a bit of trash in my time but never found a motorcycle. Best find was an antique chest.
I have three 400fours now and four in the past, light, quick handling and reliable. Plus easy to work on, top end can be done in the frame. The link for the manual is a plus of this site, and the Honda manual is the best.
Yes, the do remind me of S&W shocks....welcome, Larry