What are all open seats available to you?
12GL won't be very good for communicating. There is too much front/back offset. 12DG would be better, but still not great since angled so far away.
Odd-number middle pair would be much better, or potentially an even-number AD / GL pairing forward of row 8 (inclusive). The latter trades one negative for another, if only even-number seats are available.
Everything You Want to Know About Where to Sit on a 777-200 Polaris/PremPlus seats