I'm pretty sure harvesting professions allow you to learn the BC level stuff if your skill is 275 (so you can actually raise your skill higher than 300 by harvesting old world nodes). Not sure what the player level is, maybe 50?
Harvesting in Azeroth gives you skillups till about 340, and you can get skill limit 375 at 275 with lvl 50, as is usual.
Actually with leather working you can get recipes that kick in prior to 300 skill same with blacksmithing. I just raised up some characters through those skill levels recently and was kicking myself that I wasted so much time doinking around in the old world doing leather working when I already had the materials to make outlands level items.
Lowest LW patterns are Knothide leather, Wild/Thick/scaled Draenish items, which are 300.
Lowest BS plans are Fel iron/chain, Fel iron rod and weight/sharpening stones, which are 300.
Can you point out a pattern that uses Outland materials but under 300?