Check those tank tops carefully for pin holes, and make sure there is plenty of paint on them to prevent future corrosion.
I have worked on 14 tanks, and several had lots of pin holes in them which lets water in very easily.
Also push electrical wire through the outlet pipe to make sure it is clear and not full of sludge. Put about 2 pints of water in the tanks and make sure it comes out of those pipes easily.
Also check the fuel gauge sender is not all rusted up, as they rust easily.
Finally, run a 1/4" UNF tap through the nuts on the brackets so the bolts go in easily when the time comes to put the tanks back in.
When you put the tanks in, put the bolt in nearest you (bottom rear) first, and it makes the other bolts easier to line up. Be prepared for lots of spanner rash as your arms take a pasting when you or working in that confined area. The fibreglass rubs on your arms which is only noticeable when it is time to wash up. A 7/16" ratchet spanner is the best way of tightening those bolts.