Hi,
If you merely want to drain the system,why dont you take the radiator drain plug out ?
I've got a handbook somewhere i'll dig it out and have a look later today and get back to you
I've never bothered with draining the block on any engine, assuming you are doing a coolant system flush?
I just remove radiator drains or bottom hose. Flush with a hose pipe then put all the antifreeze in neat first. Top up with water & run to mix it.