Firstly, pictures will help show exactly where you’re wondering if a seal should be, but without any, this is what I can offer:
Normally there is no seal around the water pump housing and driveshaft for keeping water in the pump. Underneath the plate the impeller sits on is a seal, but that’s so the gearcase oil doesn’t leak out. Also, since the engine is new to you, it would be a good idea to check (or change) the gear oil before running it.
At the top of the impeller housing, there may a slight gap between the housing and the driveshaft so there’s room for the driveshaft to spin without rubbing. I’d say it’s unlikely a seal goes there on your motor, but I have not worked on your model of motor before, so can’t say for sure.
Sometimes, at the top of the driveshaft, where it goes into the powerhead, there is a groove under the splines for an o-ring. Having an o-ring there should stop water that climbed up the driveshaft from continuing up to the powerhead. I think the powerhead has its own seal though, so maybe the o-ring (if applicable to your motor) might just keep water off the splines so they don’t rust together. Not sure. But hope this helps you identify where and where not there should be seals.
One final thing. When testing the motor in a barrel (and I guess this applies for on the boat as well), make sure the water level is up higher than the impeller before you start the motor. If the water level is too low, the pump might not prime and all your water pump work could melt away.
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