Z-bar frame brackets were welded on A-body frames till '68 A-bodys then they were bolted on.
For a '66 GTO or LeMans:
pedals...'64-66 A-body ('67's are different)
Z-bar...'64-66 V8 LeMans
bellhousing...stock or SFI blowshield
flywheel... stock or steel
big rod from pedal... '64-66 Pontiac A-body
throwout arm adj rod... HD MrGasket
throwout arm...good unworn stock (not aftermarket)
shifter porch...'65-66 A-body
Shifter..whatever you can afford...
Nice console, see shifter...