I can only wish you good luck for that, Pepper, these are no easily found infos. Much of what you're liable to find will be educated guesses in the best case.
Some hints already:
[g]Marine brigade orbat[/g] (current standard):
-1*Marine mechanized regiment which includes:
---2*light tank battalions (on Type-63A)
---3*armored marine battalions (on Type-86 aka WZ-501 IFV and modified (better water speed) Type-63/89 APC)
Other brigade units (i.e. not included in the above rgt, this list post thing is a mess
):
-1*Marine infantry battalion
-1*Amphibious SOF battalion
-1*Missile battalion (HJ-8/HJ-73 ATGM plus HN-5 SAM)
-1*Engineer battalion (includes NBC defence units)
-1*Commo/EW battalion
-1*Amphibious recon company (combat divers)
-1*Transport company
-1*Security company
This shoud provide you a baseline organization, battalion-level units seem base on the PLA standard, and the materials will generally be high-end enough (though no heavy stuff like Type-98G tanks or PLZ-05s).
Oh, and the Southern Sea Fleet apparently includes a second Marines brigade (164th) since 2001.
For further info on the PRC forces, I can recommend you two websites,
this one which lists regularly updated articles about Chinese units and equipments, from which I got most of the info above.
And secondly you can look
this other post for fresh first-hand info, with the risk of the source info being mainly deception, as it is based on official PRC sources!
Best luck again!
Plasma