Unfortunately no. You can take the 1Z0-809 exam, but even if you pass you won't received the certification title from Oracle. You have two options:
1) Take the OCP 7 exam (1Z0-804), then take the OCP 8 upgrade exam (1Z0-810)
2) Take the OCA 8 exam (1Z0-808), then take the full OCP 8 exam (1Z0-809)
There's an on-going debate on the forums about which path
you should chose, but I recommend #2. And not because (full disclosure) I wrote a book on each exam. The 1Z0-804 and 1Z0-810 exams will both be quite difficult since they are OCP exams, whereas at least the 1Z0-808 OCA 8 exam should be easier for you since you already passed the 1Z0-803 exam. Also, the OCA 8 exam should be a nice warm up to lambdas that you will need to know for the OCP 8 exam.
In other words, I would focus on taking the OCA 8 and knocking that out quickly. If you successfully passed the OCA 7 exam, you have very little to learn to pass the OCA 8 exam. On the other hand, the OCP 8 exams (all of them) require a lot of studying!