Hi Philip,
l am doing a 1HZ clutch now,seems like it has a unique clutch compare to 2H,275 mm,bigger pilot bearing and diff release bearing,l got mine from 4wheelauto in Edmonton.
The rear spring l bought from ZEAL in Japan.The rear springs are superlong,front springs are the same as any 70 series.if you can't find rear springs,just get oldmanemu rear springs for 45 or 75 series and use your 77 main and second leaves,seen it done.
You can probably get them from TLCcruiserman in California.
Simon
TLC import
Winnipeg