High clamp is the same as bottom swing, because the mech swings below the clamp
Low clamp is top swing.
Neither of these are to be confused with top pull/ bottom pull.
So you want a high clamp or bottom swing that is bottom pull, or dual pull.
Alot of derailluers are dual pull these days.
Something like this.....
http://www.jensonusa.com/store/product/FD305A01-Shimano+Deore+Xt+M771+Front+Derailleur.aspx
Low clamp is top swing.
Neither of these are to be confused with top pull/ bottom pull.
So you want a high clamp or bottom swing that is bottom pull, or dual pull.
Alot of derailluers are dual pull these days.
Something like this.....
http://www.jensonusa.com/store/product/FD305A01-Shimano+Deore+Xt+M771+Front+Derailleur.aspx