Cooling system isn't as bad as it sounds, but there is a procedure you should follow, which is documented here:
http://www.matraclub.org.uk/faq7.html#twoI can add that the easiest way to drain the system is to take off the lower radiator hose in the front end and drain it from there.
I'm afraid I can't help you with spotting the timing marks, but on the 2.2 they are most easily accessible on top of the flywheel through a cutout in the bell housing.
Good luck