When to raise H.U. against a player who never folds pre-flop

[bcubed72]

I was playing a $30+3 SNG tourney on Pacific Poker today. Eventually, it got down to HU action, me with T2500 and my opponent (an aggresive player) w/ T7500. As the chip lead seesawed back and forth, I noticed that he NEVER laid down a LB. This raises the question of when to raise. The standard I used for raises: 1. pocket pairs down to 66, 2. A-anything, 3. K-8 or better. I did okay against him (ultimately winning w/ 88), but I wonder if my strategy is sound. I am a winning tourney player, but have experienced fewer 1st place finishes than theroy predicts (10% 1st out of 46% ITM: about 120 sessions). How loose of a raiser should I be in this situation, and if I raise too loosely, aren't I opening the door to my opponent limping w/ KK or AA, only to reraise?