FWIW, there were no 6 speed Shimano brifters ever AFAIK, and the only 7 speeds were RSX. 8 speed spacing is close enough to 7 speed that the 8 speed levers and derailleurs will work with a 7 speed cassette; just don't mix 8 speed DA with anything else as 6/7/8 speed DA has incompatible cable travel. Otherwise you can fit 8 cogs with 9 speed spacing or 9 cogs with 10 speed spacing on a 7 speed HG hub; 6 speed freehub bodies are naerower, not easily HG compatible, and you'll lose at least one cog.
8 speed Campag has now been out of production for decades, so not a great option, and the spacing is enough different from Shimano that Shimano wheels and cassettes sometimes won't shift properly. The later Campag levers are a better shape ergonomically too; I'd only consider 10 speed minimum as all the 10 speed stuff is compaible, not the case with 9 or 11. (But realistically I'd stick with Shimano for multiple reasons; YMMV.)
Later,