Steviep,
I have been going through the same process. But I think my dealer told me none of these kits were available any longer except for the power beyond.
I have ordered it and it is waiting at the dealer for me to pickup.
I had wanted to add the 4th and 5th valve kit so I could use it for TNT. That kit is not available and does not even come up in JD's system any longer to check stock at other dealers.
I am headed toward just installing a 3way Prince valve externally into the PB similar to what Jim did but wanted to exhaust all options for a factory system first because it would be much cleaner.
Would you mind sharing which dealer you are talking to and I may try contacting them for my needs?
BTW, if you think you may ever want to have PB on the tractor, now would be the time to do it if you do install that 3rd valve. It would save you some labor that way. The PB kit runs about $300.
Good luck,