[Jim Maxwell]

The original 289 grille is a valuable item for an owner of an original 289 that needs one. If a magnet sticks to it, it isn't aluminum. This looks like an original to me. E-Bay would possibly be a good place to sell it. Regarding the seatbelts, those too are rare and would be desirable to an owner of an original car, but I would hesitate to trust my life to 40 year old belts. Most racing series require belt replacement every 2-3 years.
Those begin said, I would be interested in the original belts for one of my cars.

Jim