A buddy and I are trying to revive a '78 Johnson 115HP. We started by reading BoatBuoy's fantastic sticky on awakening a sleeping outboard. It's been really helpful. We've taken it slow, solving electrical problems and some stubborn cylinders and now we are on to the water pump. This engine has been in storage since 82 and probably only saw a handful of hours since it was bought new in 78. I took off the lower unit (which had a good amount of sand imported from the Keys) and opened up the water pump. To my surprise, the impeller looks good as new. It's still pliable with no cracking or dried up bits There are no signs of wear or rubbing inside the pump.
Question is: What am I looking for? Is this impeller good to go or should I just replace it on principle? I already bought a new impeller based on the assumption that the 30 year old one would be trash. It was about $50. I would love to apply this to some other needed parts if I can. Thanks for any expert input.