Before I head on out to the model store, here in Atlanta USA, I need to know
how well code 83 US track would match up to the SMP Code 75 track (The code
83 would be used in Fiddle yard, I already have code 75 Peco turnouts) as
its expensive to order code 75 from UK and no one around here has any.
So much depends on the sleeper thickness of the various makes of track
that its impossible for us to advise you on that, just buy a bit and
see for yourself. Whichever track is lower can be raised with paper
strips Check how many layers you need to bring it level then cut
stripe each 2 inches longer than the one above to give you a gentle
change in level.
SMP code 75 is bull head rail equivalent to BS95 rail at 4mm scale.
Code 83 rail is the equivalent of BS113 rail at 4mm scale and these
are commonly joined by junction fishplates in the real thing.
Peco code 75 is flatbottom rail and does not match any UK rail at 4mm
scale, its effectively the equivalent of the BS113 rail but to H0
None of which matters so long as you shim the track to get the rail