Aye, that would be me - exact same situation. Dead fuel pump, and a Prins system which won't start on gas. I have another GC which runs a King system, and that'll start on gas, but not the Prins.
You can see the fuel pump gasket arrangement here - http://www.ebay.co.uk/itm/Fuel-Pump-Ass ... Swe-FU-CBr
- that's the same one I bought, works fine.
And it looks like you have knocked the pressure regulator off the top, so will definitely need a new one!
I just knocked screwdrivers under the lip (after taking off the metal retaining ring, which I see you have done) and it gradually came out - then it bounced out and threw petrol everywhere when I lifted it out.
If that hadn't worked, knowing what I do now, I'd just knock screwdrivers through the side of the pump where necessary, as you'll be replacing the entire module, and yank it out like that. You don't need any of the old parts - the new pump comes with regulator, gaskets, everything.