Welcome to the forums.
I went to the historical society for the road I wanted to find the answer to the same question. Give Milwaukees HS a try.
Good luck,
Richard
What Horns were on the Milwaukee Road SW1200s? Specifically no 625. It later became Canton Railroad 1201, later 1203. I'm building a model of it and believe it retained the MILW horn. Very melodic. Thanks.