They didn't put a nice coolant drain valve anywhere on the MK1.
Just pull the lower radiator hose and have a wide container?
That doesn't drain the block very well.
Pull the thermostat housing? There's a mess.
There isn't a nice way to drain the block when draining the cooling system for the MK1.
In walks "The Easy-Drain" setup (to some dramatic music):

waterpumpdraintap by
vwfatmobile, on Flickr
I tap the lowest part of the waterpump housing to 1/8" NPT.
Then plug it with a square head plug.
When I first tried this I thought putting a brass drain valve there would be a good idea.
A 1/8"NPT brass valve with a drain hole down through the center doesn't have much metal.
It snapped off mid-flight and we lost a good engine that day.
Lesson learned: use a plug.
To drain the radiator, I loosen the lower radiator hose clamp and slide a flathead screwdriver in between the flange and under the hose.
Coolant flows down the screwdriver, hits the handle and drops in a container.
If you have power steering it will be in the way, making this "The Not So Easy Drain" (less dramatic music).