Oil change

Prob every 3k oil and filter every time if with dino oil, you can stretch it some more with synthetic, but still change filter every 3k. Add a rare earth magnet to the outside of the filter cartridges to help strain out ferrous dust. Check oil level every 1k or so because of possible oil leaking past old valve stem seals. Top off as needed between oil changes. At least that's what i would do. If its original 60k mile engine from 1973, it's got a flat tapper cam I recommend using an additive called ZDDP with the oil. This adds back in some of the chemicals oil companies removed to prevent wear since everything new is now using roller cams.