I don't know the differences between the Opemus II and IIa, but perhaps it's one and the same enlarger? I can't find Opemus II on http://www.meopta-history.com/?id=312.
Anyway, I used to have a Opemus IIa, a simple, small and sturdy 6x6 enlarger. The negative carrier is excellent. But you will need to upgrade the lenses, the Belars are not stellar performers. You will most likely need new 39mm lensboards too. Fotoimpex in Germany sells them I think.