i dare ti doubt that you should use 205 50 r15. I think it's rather 205/55 r15 or 205/50 r 16.
The 65 r15s might rub on full lock or full Suspension compression
1996 855 R,
black on black, M56 swapped, Quaife, TME 2.5 exhaust, 17 inch Volants
2010 V70 D5,
Saville Gray on tan leather, 18 inch Odysseus
65s would be 2.4 inches taller than the 50s(23.1in). Is the wheel well in a GL the same as a turbo? Because a turbo has 205/55R16 tires that are 24.9 inches, that would make the 65s only 0.6in bigger than tires that barely fit. Might be worth a try, but I would bet they would rub. On my turbo driver side rear, I measured 28 1/2 inches horizontally right across the hub. Of course your speedometer will be off by quite a bit, maybe 7 mph or so. 65s would also give you a squishier ride.