It would be nice having the original setup..but oh dear , all that work fiddling with springs and wire .. For a fraction of the effort , you will achieve good results using modern HD foam . With the canvas covers on, who is going to know the difference
Materials like horse hair , are not that commonly used these days with upholsterers .... and with the animal liberationists being so rampant these days ..horse hair wouldnt be 'politically correct' either .
Just my two pennies worth
Mike