I have a pretty good collection of train sounds with my modern videos I have shot from 1985-1997, and could have easily dumped those sounds into my vintage films, but as you said, who knows what whistles were on those engines, and none of my 80's and 90's sounds could match some of the speeds those engines made on the Alamosa-Durango Rocky Mt. RR Club trips.
One thing I do have is some reel to reel audio tapes I bought from Elwin Purington, who recorded some sounds in 1962 when he was with Maynard Laing. His sounds are used in my Canadian Material(Laing film-Purington Audio), which matches many of the film scenes exactly-truly rare treasures for sure!! There is one scene where the camera man(Laing) pans a 4-8-2, and near the end of the pan you see a hand on a microphone sticking out of the window of the car(Purington's mic). I was able to dub the REAL audio into many of those scenes which was really fun to work with.
Purington told me that most of the guys doing audio field recordings in those days were novices, and he didn't even learn about masking wind noise until the mid 1960's. Most of his D&RGW material is very windy, especially the Cumbres material.
He does have a doubleheader going west to Durango, that has 484 as a helper, and it cuts off someplace, and runs light followed by the train later. Each is taped at Carbon Junction in the evening blowing for a crossing as I recall. They have several scenes on the Silverton as well, probably with 2 of the 3 K28's. I know one of the film scenes shows 476 or 478 on a work train as a break-in run, as it looked like it was fresh from the paint shop. Unfortunately all these films had some sort of defect, and they all look like the processing was messed up damaging the film, so I have never used any of it, except for a couple of brief shots describing the D&RGW Cumbres runs in our "Chased by a Steam Train" intros. In those we see an oil train with a rear pusher headed to Cumbres. I do not know for sure what caused the film defect, but if affects most of the D&RGW narrow gauge films. I never felt comfortable making it into a program to sell because of that. There are also some neat scenes of 473 as the Durango yard switcher, which was okay, except the film speed was too fast(this can be fixed though). I don't think the audio is that great overall either to make a CD with it. Most would be Silverton related due to wind noise on the freight sections.
Cheers,
Greg