I agree that the videos I've seen of the mogul make it sound very similar to the 8Fs and Black 5s.
I believe the main factors in a locomotive's sound (chuff) are the boiler pressure, super heating and cylinder number and size (all 3 are super heated and have a boiler pressure of 225lb, the 8F and Black 5s have 2 cylinders 18.5" x 28" and the mogul 2x 18" x 28").. When you think that in 00 the models are 76 x smaller than the real thing, it ought really to be close enough, especially if the project can be 'built' with the correct whistle.
I'm currently using a BR std 4 sound for my mogul, its not perfect but will do for the moment...
The one I'm struggling to find a sound for is the Horwich Crab...