72/144 hour visa - arriving shanghai, but outbout flight is via Beijing

Hi. I am arriving China in Shanghai Pudong, departing approx 38 hours later from Hongqiao. My flight out of China however is via Beijing (2 hour transit). I thought I was OK, with the transit visa given I arrive and depart Shanghai, but reading here, it seems I may have a problem as I physically exit China from a different airport that I arrive.
If not possbile, it seems though that I am OK however with a stop over in Shangai of less than 24 hours though.
Appreciate advice on this.

Thanks.