swapping 82 727 parts into a 78 727 transmission case

I have a 1978 American Clipper 727 big block trans that I would like to rebuild (440 with Summit Racing FI already installed). I have an 88 727 smallblock trans that I rebuilt many years ago that was the "backup" trans for my 83 Ram that I have since sold. I don't need the rebuilt SB trans any longer and I was thinking that I would tear it apart, save all the internals, tear the BB 727 apart, have the case cleaned ,buy new seals and put the SB parts into the BB case and save myself some clean-up time plus put the newer parts to use. The SB trans was given only the best hard parts at the time of rebuild, premium clutches, bands and a shift kit. Both trannys are non lock-up. I have a brand new gear vendors in the garage that would also be installed at the time of reasssembling the trans. Anything come to mind from anyone that might be a problem as far doing what I have planned? Will the later valve body work OK in the earlier case? Should I have the convertor rebuilt and hang with it or replace it with a new "RV" converter and if so, what? I know better than to replace a 5 pinion with a 4 pinion planet set if I run into that situation and stuff like that. I would assume that being a later trans that the 88 trans probably has had improvements made over the previous 10 years that could only made it better and I'm hoping that no major mods had been done as far as the cases are concerned that would make swapping from earlier to later that would make this an unrealistic project.