Reading this with interest as I am presently dealing with my wifes 107 a/c system.
Jalex, please don't flush out your drier with anything. Install a new one. There is a little bag of dessicant inside the drier that should be absolutely completely saturated with moisture since the system has been open for some time. You won't get that moisture out of there with a 30 minute or for that matter a 30 hour evacuation.
I think we should all respect the recomendations of Larry Bible and psfred who both work with these issues every day. If you do it their way, it will stay working longer and be more trouble free. If you fool around with the quick fixes of Freeze12 et all, it may work for a while, but your car won't be dependable. It's r12 or 134 for me.