HAVE A LOOK AT:
www.vwshows.com
and be sure to find out what the speciality of the particular show is. They tend to cater for different section s of the marque so dont get disappointed if you find a water cooled racing show but you wanted a air cooled heritage event.
I just did the Bad Camberg Veteran Treffen which was restricted to air cooled VW over 30 years of age. (The oldest was the 1938 KDF that came out of Lithuania.
countrybuggybill.