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 !!