Palm Springs is a very easy century with all the "climbing" in the first 40 miles. It's the sort of ride where even if you toast yourself in the first 1/2 (unlikely) you'll still be able to finish. You sound like you want to attack the ride. I'd go for it with one caveat; if you encounter high winds as we did one year I'd not push too hard during that 10 mile slog into the wind as there is little to gain in those conditions. Also, parts of the course may be crowded so exercise some care.
I wouldn't pay too much attention to speed and would completely ignore average speed during the ride - pretty hard to interpret in terms of, let's say, a desire to average 14 mph. You know how you felt during the 90 mile ride so use that to maybe up things a notch and see how you feel in the last 20-30 miles or so; that's the point at which you might look at the average to see if you can reel in that goal of yours.