Sounds like you have most of your problems work out, I went through the same thing . What a pain ! I used a 72 mercury cougar tank, and a shortend fill neck from the same vintage mustang . With my channel the cap is hidden by the closed tail gate. I had to trim my rails about, 1/4 per side, and it only hangs below the rails about2" . Hope this helps someone, because it was source of many a gray hairs. Also the tank is slant.ed up in the rear
I wonder if having an unbalanced tank might become a problem?
