Well, NVA can also mean Nationale Volksarmee, which means DDR army
But yeah, kinda funny that same three letters can have two entirely diffrent meaning.
An east German AK is alot harder to pull off unfortunatley, as nobody makes them, but if Finnish law permits it, you can come quite clouse if you can import real-steel grips.
Getting a real solid stock to fit on an airsoft AK is allmost impossible, you would need to cut off so much of it im not sure it would still work, or ever fit the body properly, so your best bet is going for a folding stock version of their AKM.
The front grips are a bit hard to find, but you see them sold on eBay every now and then, they look like this:
http://img372.imageshack.us/img372/1705/eastgermanak74handguardspistol.jpg
East Germany used a coat hanger style folding stock, so your best bet is VFC's new AIMS AEG, Iokatsu also makes an AIMS, but theirs unfortunately have Russian markings on the Reciver, the VFC does not.
http://www.wgcshop.com/pcart/shopper.php?itm=VFC-AEG-AIMS_srch_1
The real front grip should fit like a glove, but the real pistol grip will never fit, so that will look a bit wrong, sadly, nobody makes east German pistol grips for airsoft.
Maybe you can paint it or something to make it look more like the German one, that could be worth a shot.
What you would end up with would be extremely clouse to the east German AKMS copy, with a few minor details beeing wrong (pistol grip, rear sight, a few markings, release button for folding stock, they are allmost identical, but Romanian and east German Coat hanger stocks use a different release button), perhabs you could also get ahold of a real German rear sight to put on there, it would be a very good replica, not perfect, but very very good.