I used to own a Seaward 25. The boat has a very shallow bilge under the floor, but there is really no place for water coming in by the motor to drain there.
I took the pic below when I replaced the sole in my boat. You'll notice the stainless cover that a previous owner installed in the floor toward the v-birth end of the salon. This is the location where you'll find the lowest part of the bilge. We had a Rule bilge pump installed there and there's barely enough room for it there. I always wondered where the water would go in the event of a large leak, and you found out. I figured I could just open the stainless cover to allow more to flow to the pump if necessary.
I would suggest replacing your PSS seal at this time as it's probably original. Suggest the newer, vented one, though it will be harder to get in place if you have the non-vented one currently. Also suggest checking your cutlass bearing for wear and replace if there is any play. You will also want to replace the coupling and have it fit and faced to the current (or new) shaft if you decide to do any of this. It wouldn't surprise me with things being off as much as you found, that you will find the coupling loose on the shaft. If so, you'll be looking at a new shaft too. I had all that happen on our boat and got to do it all over again after a previous owner replaced the pss seal, reused the old coupling, and it loosened up on me.
Concerning the Seaward forum, there used to be a very active one at trailer sailors .com but all the trailer sailors forums got moved over to a new site and the activity on the Seaward one has mostly ceased. It's a shame, as there was a wealth of info on these boats on the old site, and it's all gone. The Seaward facebook group has some activity on it, so you could try posting questions there. Good luck with the boat. They are nice boats.