The first thing you need to be aware of is disease resistance and size Rootstocks for Pear | WSU Tree Fruit | Washington State University and a little more information Rootstocks for Pear trees . Finally to the cold hardy pear information http://www.goodfruit.com/in-the-hunt-for-cold-hardy-pears/ . Part of what your looking for has been discussed Euro pears on Ussurian rootstock - #14 by Sue-MiUPz3