1.5x0.120 wall is a normal size. For SCCA/NASA/NOPI/US Drift you can use either 1.5x0.120 wall or 1.75x0.095 for cars 2200-3000lbs.
Did you make base plates for it? Or is it just sitting on the chassis?
And since someone brought up rust and patching it, here are some pics from a car I did a couple weeks ago.
Here's what I found on the driver's side strut tower.
A little further down on the frame rail on the outside.
Engine bay side of frame rail and strut tower.
Here's what I found after I started cutting stuff out.
Had to cut part of the firewall out.
More frame rail rust.
And now it's all patched up. I used 16ga. pieces of steel.
Another shot.
Down the frame rail shot.
Shot of the patches from the engine bay side. You can also see some of the stitch welding.
Strut tower stitch welding and some of the patches.
The other side.
I also put a cage in the car. And no the diagonal isn't the wrong way, the customer is going to make the car right hand drive.
More cage pics.
Another one.
And here's the gallery with a bunch more pics:
http://www.theoryinpracticeengineeri...pwork/andys13/
Tim