Any idea what the dimensions of the ramp in the flangeways of the frog are? Wonder if it could be built without it? Wonder if the flangeway gaps could be decreased a bit if only using modern MTH Proto 3/2 engines and code 145 or 172 rolling stock? I think I will test build a #5 and 36r turnout. I will use scale ties and spacing but the inner dimensions of Ross and see what happens. I like quirky projects like this so why not? Can probably knock it out this weekend.
It has been so long I don't remember. I do remember that the MTH, Intermountain and Atlas scale wheels are 172 tread and don't really have problems with Ross #5 turnouts. My Pecos River Brass cars have a narrower tread but didn't have problems either. I converted a trio of Lionel mill gondolas using the Lionel wheel sets which are about code 145 and they worked as well.
Slipping shims into the flangeways would probably reduce the "bobble" but probably aren't necessary.
What I did find is that you get the occasional car that seems to derail for no apparent reason. I have a couple of those and ironically they never derailed on a turnout. Go figure.