904 giving up the ghost?

OK I got the 'new' valve body assembly apart and there are some distinct differences in all 3 parts. The new one is supposedly a late-70s 904 unit but it doesn't have the part-throttle kickdown module which is fine, I got used to manually downshifting anyway. The thing is the separator and transfer plates are not the same between my old 1966 version and this late-70s one so I don't want to just mix and match parts and end up having things not work right (or burn up my transmission). I bought the digital version of the Torqueflite Handbook by Carl Munroe and that was only a little helpful, I still don't understand the differences between the two units and what each of the hydraulic channels do. I really don't want to put the newer VB on the older separator and transfer plates if there's a chance it won't work and I'll have to tear the damn thing apart again.

I'll try to post some pics comparing the components side-by-side but I'm thinking at this point it might be better to just use the entire 'new' valve body assembly and perhaps modify the parts that I can to make it perform a bit better? The most noticeable non-stock feature of my old VB was the raised WOT shift points; what determines that? Is it in the valve body or is that all handled by the governor unit? Like I mentioned before aside from the higher WOT shift points and slightly firmer shifts my old unit didn't act much different than stock.