Forum member jagrick has seen the most originals of those that post here on the forum.
I believe that the original top was a front and back made of a fiber board material. The wire for the Lionel backlighting the downward shelf wiring ran through the hollow sides. There was a hole in the table for the plug to pass through where the top attached to the table.
Here's a thread by CharlieS that has an original D-133 with good provenance. Should help your work. Very nice work, by the way!
The matching green is very tricky. I think jagrick has come the closest over time. Most originals have faded over time and the shade varied slightly through the display years.