AE85/6 4AGE draining all coolant. Hints/tips

[Stealer Of Souls]

Need some hints on the best way to completely drain all coolant from the system.
The radiator tap seems to only get about half of the coolant out. Was looking in my "A" series manual and it suggests there is/maybe a coolant drain point on the block, but I don't remember ever seeing one.
I wanna drain down the radiator, block and heater system.

[sergei]

The drain plug is just right next to oil pressure sender/switch (Exhaust side of the block, between no1 and no2 cylinder).