Ok, I figured I'd give an update on the TEXT files.
So I believe the first 0x800 bytes of these are the headers. In each one it appears that there's at least this much space reserved before what appears to be the bulk of the file. That's pretty much all of the good news.
Basically these files are a bit of a toss up when doing comparisons. From what I've found out comparing the JP PS1 files to the Saturn files is that the Saturn data is larger. This could mean that the PS1 data is compressed in some way. The issue I described earlier is related exclusively to the file TEXT000.DAT. That one has what appear to be symbol tables scattered throughout it, and on the PS1 these tables tend to be a couple bytes larger throwing things off. The data in these appears to be identical for the most part, but the data in between them appears to be quite different with the Saturn data being the larger of the two.
So it would appear that the first thing necessary to make any headway would be to figure out if and how the PS1 files are compressed. Once that can be determined then we could figure out if the data is in fact the same and can be transplanted back and forth.
I am thinking a good place to start with this would be to figure out how to read the file headers and see if that can point to any clues about how to read the files and if they are compressed.
If anyone else wants to take a look at the files and possibly help figure them out I have uploaded them to my drop box here:
I suggest using a program like Hex Workshop (or any Hex Editor for that matter) to view them.