First things first, Seatguru is appalling and vastly out of date. Your aircraft is here
https://www.aerolopa.com/boeing-777-300er-type-77g
Presume you’re flying 14th June?
I’d check in and choose your seat, but do not download boarding pass so you can keep seat swapping until you arrive at airport.
Here’s the current seat map
I’d rule out thinking you’ll get 2/3 seats, I’m confident the cabin will be totally full based on this. I suspect 50E will be sandwiched between two others !
F1 A0 J0 C0 D0 R0 I0 W1 E0 T0 Y3 B1H1 K1 M1 L0 V0 S0 N0 Q0 O0 G0