I'm almost embarrassed to show this after seeing the Aluminum artistry on the Pace 427.
I've just done some of the finishing touches on my fuel tank. I fabricated and welded in the front mounts. I'd been holding off doing these as I was a bit worried about the strength of the front mounts. I had a sit down and a think about how the mount would work. Things to consider were the flexing of the tank at the mount leading to a fatigue crack. To address that I kept the mount as close to the corner as possible where it's most rigid. I also made the mount wrap around the corner of the tank to support it in 2 planes.
I need a lot more torch time to get my aluminum welds looking like a stack of dimes but they are plenty strong enough and out of sight under the car.
Here's a pic of the rear mount. These are welded to a plate which spreads the load over a larger area. Another consideration was what happens If the car gets hit in the rear? I slotted the mounts so that if the rear of the chassis rail is pushed far enough out of whack it should pull out of the rubber grommet rather than tearing the tank open.
The rubber mounting should provide some isolation between the chassis and the tank. This should hopefully reduce the noise transmitted to the chassis from the fuel pump. More importantly they should dampen road shocks going to the tank and reduce the fatigue on the mounts etc.
To hold the rubber grommets firmly in place but not crush them they are mounted on bobbins that are bolted to threaded inserts welded into the chassis.
The front mounts were a heap easier to do now that the rear suspension is out of the way.
Cheers