Fuel Cell Inlet

I'm going with my original plan for an in- trunk cell. I'll write what I want to do, reply if you've had experience with custom cells etc.
I want to employ the original fill location instead of filling through the trunk opening. This would be done using a section or sections of flexible fuel fill tube between the fender and the tank. A top fitted 90 on the tank wouldn't work since that makes the fill tube level, I'm concerned with fuel backing out at fill up. I think a fitting into the tanks side at the top of tank height would work giving fuel a draining slope. Im not too worried about fuel slosh back up the filler, should I be? Im considering mounting the tank as seen in the plan view picture, without any deck across the spare cavity. Lastly, if I retain the factory vent on the filler tube, is my venting concern over with? 68 Barracuda, 340, mechanical fuel pump, Carb. I had several test drives before the right leaf spring put a hole in the factory tank. Live and learn.
Thanks

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