Welcome to the Bolt, Michael.

Perhaps you already knew that the "L" means your engine is a 1953, in 52' the "D" meant it was in a Series 5000 truck (I don't know about 53') and the "A" signifies a regular engine, I believe, built at the Flint plant.

Your mounting bolt questions can probably be answered by you if you look at the 1929-1957 Chevy Master Parts and Accessories Catalog put online by Keith Hardy.
Look at the index for the site if you get a chance, it is an amazing amount of free information.

Here is a head start for you looking at the catalog.

Engine Mount Illustrations: look thru several pages.
http://chevy.tocmp.com/1929_57chevyparts/57cmpc0128.htm

List of Mounting Bolts and Sizes: Again several pages of info.
http://chevy.tocmp.com/1929_57chevyparts/57cmpc0125.htm

If someone doesn't answer soon, I bet you could "Search" the stovebolt site for
"Engine color" and find some info about your other question.

Hope this helps.

"Nothing astonishes men so much as common sense and plain dealing." - Ralph Waldo Emerson