I am just waiting for a synchronisation tool to come in the post. My question is what damage will be done by driving with out carbs being sync? I know fuel will be guzzled but I am dieing for a drive, is there any problems I should be aware of?

Loges

I guess one side "could" be rich or lean

Driving lean can cook and kill a motor.
It all depends how far out they are.

If it is popping and farting and back firing. Park it

If it is just just generally "not crisp" then i guess it is more a case of being out of sync rather than out of tune

Being patient is the best answer..... but...well....I understand

Hey, just tune it as best u can, cant really do too much damage... symptoms will be rough running, one side of engine pushing the other along, maybe increased fuel consumption... but you should be able to get it pretty close by ear, http://www.aircooled.net/gnrlsite/resource/articles/dualcarb.htm 
thats a link that tells you how to adjust by ear.... Another thing to check is the throttle linkage adjustment... if you get that spot on then your engine should be running pretty well. I have been driving my bus on carbies balanced by ear for the last year and 3 months... I have been getting 13L/100km so its not too bad on the fuel...

do your best and take it for a spin !!

Thanks guys...
I have also found an air leak inthe carb and inlet manifold gasket.....