After I placed and cut all the tiny pieces of styrene between the horizontal bars I glued small strips on top to give the vertical bars a cleaner look. I created a small silicone mold and casted the grill using Smooth-on 300 urethane resin. Using a pressure pot is a must to make sure all the tiny details will be preserved. The resin copy looks great and it's a the big plus that the result is not a solid resin grill that you find in standard model kits but you can really see thru it.
I decided to not just place the grill element inside the clip but to create a frame around it. This means I need to get rid of the frame that I already created on the clip to make room for the new grill.

 

Here's the LS grill in mid stage it still needs to be cleaned and perfected but it looks really good. The inset pic is a magnified photo of a photo etched Monte Carlo emblem that I bought from Scaledreams. This emblem will be placed in the middle of the grill just like the original version. Make sure to check out the Scaledreams website they offer lot's of great products for your model cars and the service and shipping handling is excellent.