Until I found a better one, I had to reinforce my original coolant tank, as well. Consider - depending on the age damage - fiber-glassing it. Cut the toe-ends off a pair of panty hose and slip the tank into them one at a time. (2 layers) Cut out for the filler and nipple. When pulled tight the fabric will conform to the shape nicely. Where required - small rubber bands can be used to conform to some of the curves. Apply the resin and when cured - trim. The "window" won't be transparent but is still viewable, and as stan indicated - a new clear viewing window can be added. That's it - in a nut-shell !
1980 KZ 1300 sr# KZT30A-009997
Always High - Know Fear !