After they have reached maturity, five to 7 years, and planted in a protected spot, Marseilles Black VS, Hanc's English Brown Turkey, and LaRadek's Englsih Brown Turkey. should be able to handle a zone 6a location, without winter protection.
With some winter protection. Danny's Delight, Bayernfeige Violetta, Hardy Chicago, Hardy Hartford, Sal's EL, and Brooklyn White.
Bob Zone 5 Connecticut