Hmmm. Well, this is what I would suggest, because I have done it.
You get a little bit of framing ( 2x4''s ) and a good sheet of 3/4" plywood, a 4x8 sheet of white gloss formica, nails, glue, and contact cement. With this, you build a 4x8 table with a shiny, gloss formica top.
Now, with a substantial amount of 1808 Biaxial fabmat and Vinylester resin (fine for
fuel tanks) and plenty of mold release wax. Ready? See where we''re going here?
You wax the tabletop well and lay out 4 layers of the cloth, then mix up resin and saturate the cloth, being sure to air-roll it, and only using enough resin to wet it out and not allow the mat to ''swim''. Too much resin is bad, not enough is bad. Get help to get started if you need.
You will now have fine strong sheets of plate fiberglass. You select a tank and lay it down on each side, mark the fiberglass, cut out the side plates, install bronze through fittings with good sealer (before assembling tanks!) then fiberglass the entire tanks together, laying plenty of extra cloth around the outside. When you''re done, the tanks should be about 3/16 to 1/4 inch thick. Plenty thick and strong, and impervious to
fuel, electrolysis, corrosion, and fit right back where the originals were.
Just a thought