I did the summit long tubes
http://www.summitracing.com/parts/sum-g9006-9
Fit good except I had to modify the z-bar. My small block is in the L-6 position, and the Z-bar is still in the L-6 mount and the swivel ball is threaded directly into the block. I think if everything was in the V-8 I'd have more room and the z-bar would clear.
I had to move the bottom arm over about 2" and bend the rod going down to the clutch arm. Not bad for a bastardized truck.