2-rail scale on three rail track

First   You will want to move this to 3RScale.  A lot depends on the track you are running.  Ross/GG/Atlas will not be any issues due to the rails being flat. Fast Track will work but the rails are rounded. The big issue will be the turn outs. For Fast track you will need to modify the frogs. There have been a few post on what to do. Curves are another factor to consider. This usually applies to 50 ft or bigger rolling stock. This also from a post I read yesterday includes Scale wheel engines with curves and turnouts.. I have actually kept all my 2R wheels and trucks. I have done some fixes with the fast Track and have a 2R car coming Monday. If all goes well I will be reconverting the All Nations/Weavers/Intermountain cars back to 2R. I am planning a new layout and this time it will be Ross/GG. I am also strongly considering changing to 2R.  Hope this helps.