Right yeah so setting in game to 900 and then setting your logitech software to 900 will actually sync your wheel's lock to the exact steering lock that each car has. This is compatible with fanatec, thrustmaster, logitech gear only, though. So you don't need to manually set it in game for each individual car if you do the 900/900 thing.
Then you can just adjust the steering ratio up or down in setup. I usually use a pretty high steering ratio. Usually around 1 click down from max. But I'm slow.
Have you given the 720 a shot? Should be superior to the 650 in every way of I remember correctly. You may be able to beat your times with relative ease! Essentially handles the same with the same super early trail braking technique, though. I think tc 1 is the go for the 720, though.
Most fast setups I've tried generally try to murder you at any chance haha.