I would try to get a set that was made for a beetle because of of the differences in weight and weight distribution between Bug and Porsche.
There are two companies in Germany that make coilovers....Remmele and K.A.W.
http://www.fahrwerke.de/artikel/ is for K.A.W. and Eddy Remmele is still working on his website. If you are in the US you have to ask aircooled.net for the Remmele ones. If you are not you can either ask teh vendors themself or ask Oliver from Power Tuning Parts to help you. Also make sure that if you get a set to get longer bolts for the 951 arms. You will have a hard time finding those bolts in a not metric country. I forgot what the pitch is but I think it was 1.25 and not the bigger 1.5 one. Check on that though.
Alex