save the tranny swap for when you do the motor too if you can. if you change the kind of block it would be a waste of time to swap out to a manual tranny if you will need to find a different one to fit the new motor, if you just change to a different, 302, 351 or 300 I6 then you can use the same tranny.
converting to manual you need
A. tranny
B. Clutch/flywheel for 302
C. Clutch pedal, mounting braket, and hardware.
D. swap out the steering column to get rid of the auto shifter.
E. Cut cable from shifter to instrument panel to keep your current odometer and gauge cluster.
I don't know about the saftey switches for the auto and manual to keep the bronco from starting in gear. for that you will need to ask someone else.
find a manual donor bronco, f150 or f250 and start stealing parts