Welcome Norwester! That's a great find and a nice HJ, is the date stamp 3 or 5/75?
Door trims are correct, do not be convinced to swap to Kinsgswood trims for your HJ also notice the dash fascia has the centre air vent filled in? That's a possible sign it is the original fascia.
Also check the vents on the side, they should be the old HQ style that spin, not the vertical/horizontal type found in later models.

Make sure you get the chassis number off the front rail and check it with the BHJxxxx on your ADR plate.