62 Lancer gas tank

After reading a bunch of threads here and on other sites I decided to go with a 63 tank in my 62 Lancer.
I cut a copy of the original mounting holes 3 inches towards the rear of the car. Now I will drill a new hole for the J bolt on the passenger side frame rail.
The fill hole lines up perfect.
The only thing is the tank ends up about 5/8 " from the shocks. (Is that to close) I have an old inner tube and some roofing felt for the strap and between the tank and floor.
Does the felt and or rubber just lay on top of the tank and get trapped when installed? My car did not have a tank at all when I got it. Any help would be appreciated! I set up the strap so it fits down in the valley of stamping of the tank, I assumed that is where it makes sense to hold in place the best. I read others have used a second strap which would have to go across the top of the stamping as in the pic below.

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