A look at the various gp parts diagrams on the Atlas website suggests that all the China drive Blomberg trucks employ the same wheel sets. It wasn't conclusive as to whether the AAR B or 3-axle EMD trucks used the same or different wheel sets. However, in a past conversation with NWSL, it was stated that the drop in set for the Atlas gp9 was the same set as would be used for the rs1. So one might infer from that information that the Atlas wheel sets would also be interchangeable.
If all else fails, I have a junk box gp60 here that has 2-rail wheel sets. They are used to some extent, as the treads show wear, but appear to be in perfectly good shape. That could take care of one of your f units. Shoot me an email if you are interested.
Don't forget that you will also need to consider pick ups and isolation when you swap to 2-rail wheels.
Good luck!
Jim
