PSS Seal
Having a 34 footer, I have no knowledge of the "fit issues" you might face... but we had a PSS seal installed when we did a major haulout soon after we bought out boat. That was about 1995.
Strictly FWIW, the one upgrade we cannot make happen is a CV Joint, because that requires a lot more room in front of the shaft log than we have available.
We needed a new coupler, and opted also for a new cutlass bearing. Shaft was fine, but was sent out for truing. No worries since, and a dry bilge.
I figured that I should approach the drive line components as a "system" and get everything done while the boat was already out of the water for a bottom job... (It is cheaper to combine jobs related the underwater bits, IMHO).
My .02,
Loren in PDX