I have the D-105 5x9 Dealer Display and spent a fair amount of time trying to recreate "Lionel green." After testing several colors I ended using Behr's Park Picnic. While the paint was wet, I sprinkled on the Lionel 919 "grass" which I obtained on Ebay.
Let me try to find some build pics. I actually think I've posted several here over the years.
Btw, on my layout I used an off-white cream rather than the gray. Lionel used both over the years depending on the particular layout. This was for the road beds and the "ballast" under the track.
The masking and painting process to obtain the classic display look is quite an undertaking. Same for mountain construction.
If you are interested in sharing ideas email me. In my Profile.