I have had great success in using a Wippermann 8-speed on a Shimano 600 crankset with modern 8-speed Shimano cassette. Also on vintage Shimano components. As far as I know, an 8-speed chain will work fine with up to 8 cogs, but 9- and 10- speed chains should be used only with their respective numbers of cogs. If you use only 5- and 6-speed FW's, friction shifting is fine, but I would recommend using some kind of indexed shifters above 8-speed.
Samuel Pierce-Ruhland
Racine WI