Edit: I'm sloow...
http://us.battle.net/d3/en/item/blackthornes-breeches
Is this link wrong in some way ? Cause the listed stats don't really allow for much variance, especially for vit/dex. The values you give for life on hit also both fall outside of the listed range.
So basically, what you want is the high-end for life on hit, and sockets (2 or 3 I guess). Life on hit can't be on non-legendary pants, so you can't directly search for pants if you want to filter for that particular stat.
The way I'd do it, is search for any type of armor, legendary quality, put the desired value for life on hit and sockets (putting 2 is good, cause then rings and amulets can't show up) and whatever 3rd stat you're looking for. With those search parameters I only have Blackthorne's breeches showing up in the results.