Database Software

Our company uses 2 apps. Both apps use Oracle on different servers. OS on both servers is W2K. Oracle on both servers is 8.1.7.4.1. Database A is in WE8ISO8859P1 and database B is in CL8MSWIN1251. DB A is a productional base DB (most data in in it).
I must execute the regular data exchange from db A to db B, preferably via db_link. Some fields in db A (varchar2 type) contain data with Russian characters (WIN1251 OS codepage).
So. I've tried to get data from db A to db B via db_link and have '?' characters in place of Russian characters. Also I've tried import/export from A to B with the same result. Any setting of NLS_LANG on the end server has no result.

That's a questions.
1. Can I get data from B to A with real Russian characters conversion ?
2. What way to exchange data must I use ?

I'll be pleased for any advice.