underbed gas tank side fill options?

[one legged lance]

Ok I am waiting for my early classics gas tank to put where the spare tire was so I can drop in a ramjet 350 into my 72 chevy 1/2tn lwb fleetside...
Question?
other than the weld in side fill door is there any side fill bolt on setups?
I called no limit eng. about the cool-cap but they say no good for side fill
...I would really like marine style or like the motorcylces have with an alum. ring that has the gas cap/neck and I can just run hose to the tank.
thoughts?
enjoy
1 leg lance