I agree with Shangrila, please do minimal restoration or just leave it as is. It is a really cool collector piece just as you have it now.
My mom has a house full of "restored" antiques. She accumulated them back in the 70s before antiques began to gain so much value. Some of them would be much more interesting (and much, much more valuable) if they still had their original finishes.
I know this is true of wooden furniture but aquariums? They're so rare that I don't think this comes into play as long as they're all original. This doesn't pertain to the glass or the glass sealant or any equipment like pumps and heaters which aren't usually part of the aquarium. Also I don't think a corroded or rusted aquarium is going to be worth more than a restored one. Just like a rusted junk car, once restored to its original showroom condition is many many times more valuable than as found.