dodge rat rod
Cool project. I'm a big fan of the '58-'60 trucks.
Since you're running an auto, you
might be able to run a set of Clifford's headers, similar to these:
http://www.shop.cliffordperformance.net/Mopar-225-High-Starter-Dual-68-Headers-55-0010.htm
I have these on my Barracuda, and while the outlets point at the z-bar for the clutch setup, it looks like they would clear a slushbox application with a little fab.
Hooker also makes their Super Comp headers to fit the /6, but they are long tube headers and considerably more expensive.