I got lucky when I converted mine from auto to manual, actually I was only toying with the idea when I found a box of parts at a swap meet tagged as "'69 firebird manual trans. parts". Inside was the bell housing, z-bar, pedals, push-rod, springs and a few other parts. All I needed was the trans. throw-out bearing and clutch. The box cost me $75.00. Made the decision easy.
I did have to put new bushings on the pedals.