The main sources are:
Urgent Fury Mark Adkin (Leo Cooper)
Grenada 1983 Lee Russele & M. Albert Mendez (Osprey)
Grenada Hugh O'Shaughnessy (Sphere books).
Articles in The Times & NewYork Times Oct.-Dec. 1983
If you wish to follow the historical events I would suggest just considering on the south-western part of the island and playing the first two days. If the US player hasn't cleared the whole area by then I would deem it a defeat in games terms.
A large number of "whatifs" arise here. Some of which I've listed in the TOEs. These would mainly depend on the Cuban backed prime minister Maurice Bishop not being executed on October 19. This seems to have lead to the poor turnout of the militia and the Cubans lack of enthusiasm to defend the island. This act was also one of the catalysts for the US invasion, but with continued Cuban & Soviet buildup in the area it is likely that an invasion would have gone ahead anyway some time in 1984.
I've played both versions over a couple of weekends with varying success! The historical encounter was a fairly easy US victory, if the PRA doesn't gain some advantage in the initial landings he's on to a looser. The whatif was much closer, the US player not being helped by one of the Ranger C-130s being shot down over Point Salines airport (Give the Cubans a ZU-23-2, don't restrict their orders and it all becomes a lot harder.
Let me know your thoughts (There's a lot here that has been recently discussed in this group - older AA vs modern planes, para drops on enemy positions and lots of Elite troops!) :-