First was a 3D map that was just layers below/above the tiles (with reduced chance to have a star, otherwise connectivity was too easy). Once we got a J3 ship we could reach far more destinations.
Later I created a small 3D map, just a subsector or so worth. Each star system has a connectivity matrix that shows relationships to all neighboring stars up to a certain distance. Easy enough to do with Apple II. Mapping out multi-jump routes wasn't easy without a nifty image generator.
Jump wasn't fixed distance or time. J1 could go out to 1.5pc or so, and time was related to ln of 1+distance with an offset, 2ish days for an in-system jump, 3ish days for jump to companion star hundreds or thousands of AU away, to 9ish days for 1.5pc. Jumping farther than 1pc tended to wear things out.
Higher jump ratings didn't cut time by much in-system or to companion stars. Jump number extended the maximum distance to J+0.5 (maybe J+1 at the upper end) and cut the differential time out to the maximum (nonlinear, maximum J6 almost 3 weeks).
Never actually got to play it...