In my own experience, if the oil pan is off, there is a date stamped in the mating surface on the rearward side that is the casting date. Obviously it's not the 86's original mill. Keep in mind you also see these in the old Celica's; you just change the oil pan and dipstick (1" difference)

20R22R History

I think LC Engineering sells the TC kit you're asking about.
You WILL need a pre-85 timing chain; there's 3 links difference between them and later 22Rx's, due to the change in block/head heights. That's why you don't go mixing between the years to put together a long block.