I'm 5'3, and have primarily sparred larger opponents, on the insistence of my sifu (also a newbie to sparring, probably only 15-25 times). You've GOTTA close the distance, otherwise he'll keep firing punches and kicks until he connects.
After the big guy takes a swing, you could try pulling him in (lap sao). It works for me on occasions, I wouldn't do it for your test though, just stick to what you know.
If you win, come back and give some advice to the rest of us pee-wees! Good luck buddy
Alea iacta est ~ Gauis Julius Caesar
Ne quis nimis ~ Solon
Nuts to cancer ~ Sanchin31