The "E" before the 248 indicates:
1. standard cylinder bore
2. -0.010 main bearing journals on the crankshaft
3. standard rod bearing journals on the crankshaft
None of the codes you have given will help ID the year of the engine (which was made from 1939-1955), but the size, 248, should be enough for selling it.
Here are locations of other casting codes - the date casting codes would be most interesting/useful.
Does your block have a
brass plate "pinned" to the block to the right rear of the generator?
(links to images posted on oldGMCtrucks.com by Rob English)