I removed the (likely original) aluminum fuel tank in my 30 year old boat, as I figured it should be checked / cleaned. Lucky I did. it had pits on the bottom, where it sat on a wood frame. I was able to dig small holes in the tank with a screwdriver. It had been leaking somewhat, as the wood smelled heavily of diesel.
I replaced the tank with the new 19 gallon moeller poly fuel tank (around $150), and it came complete with the sending unit. I think it is a no brainer to replace the old tank, if you can get at it. Even removing the engine is not a big job. Just label all wires, and don't adjust your engine mounts, so the alignment will still be good.
I now have very little worry about clogged filters, and even water (my racor never has any in it) for a few years, as the tank is so much cleaner than an old one. Don't get me wrong, I still change filters, etc, but thye will be much less fouled than if I had a bunch of crud in the old tank, getting stirred up with every big wave you hit.
While i had the engine / tank out, I took the opportunity to clean / sand and paint the engine compartment, and the engine itself. It is so much better to have it redone. Can see leaks easily, and keep everything clean.