One thing to consider about On30 when compared to HO scale, is that the scenery elements (structures, figures & vehicles) will be 8 times the area (height/width/length) of HO scale. For example, if you take a object that is 1 square foot in HO scale and enlarge it to O scale then it becomes 8...
There is a drawing of GP60T at paintshop.railfan.net by Joshua Moldover.
http://paintshop.railfan.net/images/moldover/gp60t.html
as to its drawing scale, it's not specified.
Dan
Santa Fe used both numbers and letters to identify their trains. See attached link.
http://www.qstation.org/ATSF_Train_Symbols/#:~:text=ATSF%20Numbered%20Trainshave%20the%20following%20format%20%23-%23%23%23-%23%23%20and,the%20hottest%20and%20a%201%20being%20the%20slowest.
BNSF uses letter...