I also have a 1971 Pearson 26. I have two wooden blocks glassed into the hull under the starboard locker. One is foward of the locker
hatch and one is aft of it. Sitting on top of the blocks is a plank of wood screwed onto them acting like a shelf. I rested my gas tank on it, lashed it down and drilled a hole for the gas
line into the side of the engine well. Just air out the locker before you turn on any electric and you will be fine. If you want to get fancy, you can put a piece of molding around the hole in the engine well.
Where do you sail? I sail my ancient Pearson on the Long Island Sound.