I am not even sure of the difference between G scale and the prewar standard. I have seen standard track for sale, new,tubular at the LHS. Not priced much more than O scale. Used is very hard to find. You also have to deal with manufacturer differences.

 

ok if you want standard gauge track the same as when standard gauge was popular you can get it from MTH for about 5 to 10 dollars brand new and exact to the original.