It is probably a June 1975, so GVW won't help either. Side strips on HJ-HZ Kingswood used little welded on posts for most clips, but the ends in some places had a big hole, around 10mm or so and had a screw from behind. From memory the holes were front of the guard, both ends on the doors and at the back on the quarters. Can't remember if the tailgate strip had the holes. If there is no evidence of the holes in the quarters, and it is the original body for a HJ Kingswood ute it is probably an XX7. Console mounts are the key then. Make sure it hasn't had a body swap, it may be Kingswood tags on a Holden ute body.
Send me the ID plate details, I may have it recorded with an engine number.