Neat stuff, nice job!
Couple suggestions...the engine hoist is almost at the top of its limit, there's no way it can pull that motor (or set it in place). The cross bar with the chains going to the engine should almost touch the engine, so when you start lifting it will clear the radiator.
Once you decide if this is your permanent layout you can add some traffic pattern weathering to the floor, maybe even a small amount of debris like antifreeze jugs, roll of paper towels, maybe a stack of cases of beer, whatever.
I haven't done one in awhile but now you are motivating me to do another diorama!