You are coming from 3-rail? Stick with .148 track and .172 wheels.
I have been in 2-rail for 70 years, machine my own drivers and main frames, and I have lousy luck with fine scale wheels and track.
However, if you are truly a careful modeler and an accomplished machinist, you can go with finer scale track and wheels, all the way to Proto-48 and still be successful. If you are an average modeler, stick with the tried and true components to avoid frustration.