Harmy said:

I just decided to use the LPP print as a color reference here instead of the IB print, because it looks closer to what I also saw on some 8mm prints, so it was probably what it looked like on the more wide spread versions and also because I like it better. Though I made it all a little brighter than in the LPP transfer that I saw, as I believe it probably should be, plus it's really bright on the IB print, so with brightness I stuck to the IB as a reference, since that was scanned on professional equipment.

I suspected that's how you came up with the most recent look, and I think it's a good approach and produced good results.