FYI, if you find a bar that is close they can be cold bent in a hydralic press. The 39" bars that are referenced are out of a late 80s Camaro/Firebird. I cold bent mine to be about 36" wide at the eyes. This is so it will fit between the frame rails.
Here are two ideas for finding a bar.
1. Shops that build lowriders take out the sway bars and throw them in the scrap pile. There is a shop not far from where I work and the owner has let me go through the "scrap" a coulple of times. I once bought a bar from him for $10 and did not have to go to pick a part and take it out.
2. Spring shops are always changing springs and sway bars. Again the "scrap" is just piled up until it gets too big and taken to the scrap dealer.
Have fun with your build.
Lonnie