After you get the new tank and shutoff valve installed, you might consider plumbing in a glass-bowl filter immediately after the shut-off valve. That will catch water and keep other nasty things out of your fuel pump which eventually will probably be electric. If there is water you can see it and dump it. Check occasionally. You can get water from condensate in the tank or pick it up from storage tanks at the gas station. If you live in a humid climate, keep the tank full if you're not driving it daily.
