It is 1" thick and off set just a bit too.
If I were you I'd just buy the Redline adaptor plate. It's Part # 99004.110
$45.00 and you're finished:
http://www.piercemanifolds.com/product_p/99004.110.htm
I don't have anymore images of the desert fox decals installed on a Subaru. They are super cool and you'll be the envy of all your friends. Order a set and you will not be disappointed.
I'm not sure if you've got one of these yet but...
http://www.ebay.com/itm/1970-71-NOS-Subaru-ff-1-ff1-Front-Bumper-Chrome-OEM-NEW-/380326769922?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item588d3df502