Bulgy bolt and carrier won't work without extensive modification, trust me on this. Go over to K-Var and into their MIG-ETA forums and I have a thread on this with some extensive testing and research, along with a thread on AKforum involving the same thing.
The shaft of the bolt is a different size on the Bulgy and the Romy bolts, which means the carriers are not interchangeable either. The Bulgy bolt also has a different locking lug desing, and to top it all off a Bulgy carrier will bind up in a Romy gun.
If this had been an easy swap I would have done it long ago on my SAR-3. Unfortunately the Romy's decided to use a half-assed design on the WASR and SAR, and do not supply any sort of spare parts for the U.S. market.