That was my first thought as well. But, upon further reflection, I will change my tune. Reasoning:

-international arrivals from Europe tend to be on time, if not early
-should be able to get to curb by 7:05a without much trouble
-the bus between the two airports rarely takes more than an hour because traffic usually moves pretty well on the highways
-your target arrival time in SHA is 9a, so even if you didn't get in motion until 8, you'd still be fine
-most importantly, if you are running late, you can cancel your ticket up until the check-in deadline (~45 mins at SHA, iirc) if not a bit later than that; just be sure to keep your travel agent and/or airline phone number in your cell phone

BTW, have you considered flying via PEK? Less backtracking and no need to switch airports.