I have converted several sets of Williams E-7 locos to 2 rail operation but my methods utilize the existing drive components with new NWSL wheels machined to fit the existing axles and insulated for 2 rail. The Williams axles are an odd size close to a No. 17 drill.
I just finished converting three WIlliams scale GG-1 locos to 2 rail. That job requires machining the sintered iron quill driver castings andi installing scale tires insulated on one side for 2 rail. All of the Williams mechanisms I have reworked for others have been good runners once converted despite being "China Drives".
I don't think it would be easy to install a set of 2 rail trucks from another manufacturer onto the stamped metal Williams frame with the large cutouts for the motor mounts.
If you hae access to a decent metal lathe the job is not that hard to do.
Joe Foehrkolb