My first HD was a '91 Dyna (Sturgis - FXDB-S). I still have that bike and love it. It is in the garage on the (long) list waiting for a total overhaul.
First things first - buy a Factory Service Manual for you model and year.
The Dyna is a great day tripper bike and a great starter bike IMHO. Fun, easy to ride, lighter than most baggers, carburetor (love those Keihin carbs!), simple (few electronic junk to debug) and a DIY's dream.
I would NOT be worried about the age of the bike especially if the refresh at 40K was done by someone competent. Just check the obvious (no accident damage, tires good, nothing leaking badly, etc.). I would think that Stage 1 has been done by now, but if not then add that to the wish list. I would plan on doing ALL fluids right away including brake fluid (two reservoirs), oil filter and spark plugs (I like Champion). Check the meat left on the brake pads. If not doing Stage 1, check that the air cleaner element is clean (clean it if serviceable or replace) and see when the battery was last changed out. If 5 years or more, put that on the wish list. Get a battery tender and wire it up so you can keep it plugged in when not riding. Put heavy duty battery cables on the wish list. Check out the shocks and fork to make sure neither end is leaking. Shocks on the rear are a piece of cake to swap out (just do them one side then the other). Front forks are a bit more to do, but still simple. If the bike has been sitting, dump the gas and get some fuel system cleaner to add to the next few fill ups. Lube the neck bearings. Check out the ignition system, and if OEM, then put an electronic one on the wish list (I have Spyke w/single fire Spyke coil, but they may not make ignition modules anymore).
All the rest of the stuff is mostly cosmetic and tweaking it up to be YOUR ride.
Cheers,
TQ
