book time is about 10-12 hrs at shop rates(1000-1500$)+-,
a good supra owner can do it in about 5 hrs labor plus parts... i did mine for about the cost of the head set ($250)and to have my valves lapped and valve guide seals installed and valves adjusted.(60$).... and the head surfaced, ($75)
but i also did water pump and timing belt while i was there.. again time and parts extra.