ID question on 383 GTS

I'm sorry if this could be a repeat question.
I acquired a 68 Dart GTS. The car has been thru alot of different owners. One owner tells me it is the original engine. What I have read is 68's were stamped with a order number not the VIN? The number is stamped on the top of the block where the transmission bolts up. I do have that number which is 8G239139.Above the starter there is another number .PT383P24480348
Casting date is 3-28-68.
Under the back seat I found a table spoon of the build sheet. Mice have ate the rest.
Does anyone want to take a stab at what I have?
Thanks
Jim

This same number (8G239139) should also be stamped on your radiator support and drivers side trunk rail.