The factory started putting 904's in various heavier cars sometime around the middle of the 1970'a... my daughter at the time, had a 360, 4-bbl-powered Cordoba that had come from the factory with a 904. I asked my transmission friend Len Schneider about it (he has built drag racing transmissions for a living for the last 30 years) and his response was, "727'S have so much rotational inertia, that the sheer mass and weight of the internal parts wears them out and causes catastrophic component failure; they do it to themselves... it's not the torque you put through them that tears them up... it's self-inflicted."
The fact that the Hemi Challenge NHRA racers choose to run ProTrans Torqueflites (which are based on 904 internals) in their 900 horsepower race cars tells me that a 904 can be built to take anything a small block 340 or 360 can dish out.