Edit: (I corrected Code 140 to Code 143 below)
First question to you : Have you already bought this kit?
Ah, seeing that you have this in your stash, I guess you have.
This is all problematic, but I have some ideas.
1) Track gauge = width between the two rails
2) Rail profile = You will want a 'flat bottom rail'
3) Gauge = size for scale modeling. I think the appropriate gauge for 1:72 is Gauge OO (from memory, not 100% sure)
4) Code = rail height for train hobby
5) Track fasteners. The kit uses fasteners that is molded into the ground part, but creates for some slack/hole if adding Code 143 metal flat bottom rails, instead of the kit's 5mm tall rails (iirc).
Btw, for the Peco Code 143 product, you can also buy separate fasteners for the metal rails. But only for Code 143 but not Code 100 (the smaller rails).
My investigation indicate that the ideal gauge is CODE 100 (but kit wheels ought to be smaller anyway so, better with Code 143). An alternative would be CODE 143. Iirc, Code 100 = 0.1 inch and code 143 = 0.143 inch.
The product code for the loose/separeate Peco Code 143 flat bottom metal rails is IL-7FB if you want to investigate further.
12. March, 12:26