I have one and will lay rails on a flat to replicate it in operation.
What size rail would be best? HO or N ?
It just struck me that we have been talking about the size of the rail by the code number, without explaining it. assuming that you would know what we are talking about, but since you ask about rail size by HO or N, you may not know what we are taking about.
The code is a numerical measurement of the height of the rail, and I believe it is equivalent with thousandths of an inch (my artistic oriented mind has trouble with numbers and such).
In any case most HO track is code 100. It is grossly oversize for most applications. I think some rail gets almost that big on the heaviest mainline sections in the Northeast.
Code 83 is smaller, with a scale cross section that is more appropriate for modern heavy use main line in Ho scale.
Code 70, is smaller still, and with a thinner cross section, appropriate for modern branch line or turn of the century main line. some N scale track is close to code 70 in size but has a different cross section
code 55 is smaller still useful for narrow gauge or logging lines in HO.
Code 40 is the smallest rail I have personally worked with, it is so small that a rp-25 flange uses the whole height of the rail as a flange way, leaving no room for spike heads. when I have used it I have made every fourth tie out of PC board, and soldered the rails down.
I use code 70 on my main, and code 55 on my sidings. I chose code 55 for my log cars because I thought it would look odd for the rails on the log car, sitting on the siding to be heavier than the rails on the siding.
Bill Nelson