"Are there any places where the telegraph poles still stand along the South Park Line?"
My last trip through was 2002. There were still poles up above Webster, west of Como, and a long stretch still up along the straight grade paralleling 285 as it climbed to the CM grade crossing. Scattered poles remain all the way to Gunnison.
Key point here: If you plan on field searching this stuff, be aware that there is an intense issue of private property in much of ranch country in Colorado and one should take the time to secure permission to get onto private property. By asking in Fairplay and Buena Vista, I was able to get names of landowners and get clear passage to scout around without hassle. Be prepared to show people what you are interested in, maybe with a photo album or a few artifacts. More than once I have enjoyed a ditchside chat with authorities when someone thought I shouldn't be there. Much easier getting permission, and sometimes these people know stuff you are looking for or have artifacts themselves. Well worth the effort.