GBBRs make more sense than AEGs for bullpups but aside from SRU kits which aren't my cup of tea, your options are limited to the Groza (hen's teeth), the Tavor (hen's teeth and also crap), the WE L85 (spotty but ok unless you're a lefty) or the GHK AUG (good if you like that sort of thing)
It'd make a pretty good airsoft gun and with the modularity if the real gun it's a marketer's dream with all the aftermarket parts you could sell for it.