My 73 is in the body shop having some modifications done then a paint job. Haven't decided on colour yet. Anyway i need the following parts: Door and window rubbers (I think I may have got some from eBay but getting more would be good): orange reflectors for the front light clusters (both sides). Erik has found one - I live in Spain so having some spares may be a good idea. A steering wheel - or a very good cover if one exists: and the arm rest part on the drivers side door.
Www.steelerubber.com https://www.steelerubber.com/search?year=1973&make=buick&model=riviera&style=2-door-hardtop
Use SEM dye to change the wheel color as needed. Preparation of the wheel before application of the dye is very important. Post a picture of the "orange reflectors for the front light clusters (both sides)" that you need.
The Buick factory Group number for that part is 2.589 or thereabouts. Perhaps someone can help us out by verifying the part number that you need.