I got my sway bars from Rocky Mountain Motorworks.  They were 
$245 for front and rear, with all the hardware.  I had originally
bought some from J.C. Whitney but I returned them.  They came
with hardware that didn't seem like it would work, and I was doubting
whether the bar was really for a bus, and not for a bug.
I never did figure it out.  It might be worth another shot though
because a lot of J.C. Whitney's parts seem exactly the same as
the more expensive brands, only without the name.  I guess I really
don't know.  Maybe my order was just screwed up.  Yes, I do believe
these sway bars would work just fine on a '74 too.  If you have any
doubts, you could try calling Rocky Mountain Motorworks (The Bus
Stop).
 
Doodle Roach