I have seen Kwiklifts at the car shows, but am not familiar with the 'feet' on the high end. I assume there are rubber feet to keep it from scooting on the floor when you drive up (or winch up in your case). If that's correct, you should be fine, the winch should be strong enough. We have used one several times to load/unload my sedan onto a trailer (before it was running).
If it doesn't have rubber feet, or something to keep it from sliding, you might be better attaching the winch to the front (high end) of the kwiklift itself, instead of the floor in front of it.