Can you change vent and filler tube

If you can silver braze/ braze/ weld, I would not be the least afraid to mod the late filler. I was thinking of "slanting" the 1/4" vent into the filler neck so that it sticks up very little then "maybe" just notching the quarter panel hole for clearance. If you do that right, you should be able to have the flange/ gasket cover the notch

I used to do this when installing schraeder valve stubs or sight glasses into large refer tube Drill/ punch a hole, then use a large awl to deform the hole so it's angled. In this case angled steeply. Lay the 1/4" in there bend it some so it's lying flat as you can against the large tube, and silver braze it into place