I'm doing the exact same thing on my march 1977 120Y (aussie B210)
I jave already installed the pedalbox in my 120Y

you will need:

the gearbox/tranny, (of course )
the flywheel,
the clutch plate,
the pressure plate,
the driveshaft/tailshaft,
the spiggot bush out of the end of the crank,
all associated fastners/bolts,
and maybe the yoke of the diff

I haven't done the gearbox conversion, (I have a wandering driveshaft/tail shaft - it grew legs) but the pedalbox was VERY easy, two bolts holding the steering column up, another two holding the pedalbox to the bulkhead (those two are a bitch to get back in ) four bolts holding the pedalbox to the firewall and another two in the engine bay (they hold the master cylinder if the car has a hydrolic clutch) - you will also have to remove the clevis pin attached to the brake booster

I don't know about US B210's but Aussie B210s (120Y's) have a cable clutch