I'm sure you'll get your question answered here but meanwhile,
There's a guy named Richard that does youtube videos for precision transmission, you could try hitting them up. That guy takes apart a transmission and explains every part in one breath.
He does talk about lever options for chrysler trannies but I don't remember if it's in the above video
That channel is great, learned a TON from watching his videos. He doesn't mention the lever ratios in that video but towards the end around 35:00 he talks about using proper servo springs to make sure the bands don't come on accidentally due to cross leaks, then around 36:00 talks about blocking the inside of the low/reverse servo "apart" for the quickest possible low/reverse band release on a manual 1-2 shift.
In Appendix C of the Tom Hand book there are "recipes" for high-performance TF builds, all of the ones for 904s recommend the 3.8 or 4.2 ratio. I'm not going to say more as I'm starting to go down a rabbit hole here and I'm not an expert lol. Does your shift kit mention blocking the accumulator piston or changing any of the servo springs?