Take it outside and crack it off.
Seriously? Have you no idea of the laws you go around breaking on a daily basis?
Under the Environmental Protection Act 1990, the
deliberate release of refrigerant into the atmosphere is
illegal. The use of R12 is now banned in the UK.
So don't 'take it outside and crack it off' especially not as (and I'm using this in the loosest sense of the word) professional mechanic.
Source:
http://www.hse.gov.uk/pubns/indg349.pdfLen, take it to a garage and get the refrigerant discharged, then remove the front of the car - it's key to easy access to the motor and gearbox.
If I was doing what you're planning on doing I'd just hook the motor and gearbox out together and attend to them on the floor/stand/crane.