I used a washer reservoir/coolant overflow combination from a fox body Mustang, mounted on the passenger inner fender, close to the radiator, as you mentioned, lots of unused space there.
I would like to see it if possible.
Mine is right up against the cowl pinch weld.
It’s all done now except for soldering the power wire.
Told my Grandson & his sister I would teach them how to solder, so it’s waiting till after today’s birthday party for one of the other grandkids.