On the pouch that the owners manual came in originally, there is a maintanance schedule printed on it. These are available repro. I'm a mechanic by trade (ASE Certified Master Auto Technitian), I just follow that same as doing a customers car. At oil changes, change oil filter, check air filter(s), grease all fittings, tire pressures (I usually rotate mine at the same time) check brake adjustment, all lamps, all fluid levels, and clean battery terminals if needed. If you still have the points style ignition (I don't), checking dwell and timing wouldn't hurt either. You should also test the coolant twice a year (spring and fall) for at least boil and freeze protection, they have test strips that test for corrosion protection now, too.
