A vigorous San Jose Juniper does back bud very nicely. However, when pruning to stimulate back budding, I find it best not to prune behind the most interior greenery on the branch to be pruned (in other words, leave some green on the branch). With a very "leggy" San Jose, this may mean that you are chasing back foliage for a little while before it is as close to the trunk as you like. And of course, as with any Juniper, how well it back buds is entirely dependent on how vigorous your particular plant is. Best of luck.