Likes been said yes most lurchers ( and most dogs for that matter ) will get over a 6' fence, I had a first cross that would jump on top of the 6' run fence from sitting (Never cleared it just jumped on top of the fence then pushed off) ...
I know a lad off here had a 3/4 bred dog that i saw go over hedges after deer (Pre-ban) and them hedges must be between 4/6'high and and about 4/5' wide and he honestly use to clear them at full tilt without breaking stride after his quarry.....
But if you think about it a lurcher say 26/28'' could almost stand up on it back legs and be