If your a little foggy on it all here is how it breaks down...
Below is a dual port livewell pump. You'll see three threaded ends, The bottom blue male pipe threads into the seacock (ball valve) which is screwed onto the through hull inlet strainer pulling water from under and through the hull. The top white female port is a water outlet that the pump drives water to the livewell. The lower blue female port provides a connection for the washdown pump to draw raw water.
The earlier Gradys used a washdown pump with a diverter valve to serve both the washdown pump and livewell. It isn't really done that way anymore. Livewells use a dedicated pump designed for that purpose.
The dual port pump is the way to go now.
Below is a pretty good shot of how it'll look but this one is drawing the water through the transom. The problem with that is it will be high and dry when the boat is on plane. The other much bigger issue is that any through hull fitting below the water line must have a
bronze shutoff valve (seacock) that you close before you walkaway from the boat at the end of the day. You don't want to return to find your boat sunk at the dock. It also saves your but if a hose bursts. This livewell pump shown is a red and white Rule unit. Its best mounted straight down pulling water through a
bronze strainer which provide water under any condition. Note how the washdown pump is mounted with the motor above the hoses so if it leaks it won't be continuously pouring over the motor.
(though the motor is supposed to be water tight that is how the installation instructions recommend it be done).
Here is a video showing a little more on it.
https://www.youtube.com/watch?v=17MbYlVR_Mc
Now on the space you want to use, I know Grady would sell it outfitted with the full option providing raw water, then like mine just having a pump that's sitting in the well recirculating the same stale water or nothing at all making it a glorified ice chest. The big question is where does this empty out to? Overboard or into the bilge? If its overboard you can probably make it a well. I did that with my forward fish box. But I also sealed up the upper edges of the box to prevent sloshing water from getting into the bilge.
I'm hoping your taking about the well at the starboard side on the stern. It should have a drain that empties on the starboard side. That is what Grady had intended to be your livewell. If that's it go for it! I'd also advise you to shop around getting what you need from mail order or even West Marine before you go to the Grady dealership. You'll end up with the same equipment but at a fraction of what Grady will charge you.
This is a little more of how it should look, a
bronze strainer with a
bronze valve and the pump attached directly to the valve.
Notice how I stress
bronze? Don't go cheap on those two parts, a few extra bucks will save you from disaster.
Good luck with it!
Mike.
PS- One last note if you have to install a through hull strainer it cannot be mounted in front of a transducer. The strainer will disrupt he water flow enough to adversely affect the transducers performance. Just mount the strainer opposite from the transducer.