If you would consider a new GS grille, Frank McIntyre makes a beautiful 69 repro, ready to bolt on, I believe. He is buicfrank on the board, just PM him if interested. Otherwise, used Skylark grilles pop up now and then, here and Ebay. Good luck!
TA Performance is now stocking the reproduction `69 grilles and they are ready for immediate delivery.
69 grill I have one but it comes with the surround and side brackets, 500$ and I'll pay the shipping Steve T.