Tyres usually have an “ideal” foot print on a specific width range, if your wheel is narrower than the ideal width range then the result is sidewalls bow resulting in a squirmy mid corner.
Tyres that are mounted on wheels wider than its ideal foot print may result in the “stretched” sidewall which doesn’t create the ideal contact patch and results in reduced grip.
High horsepower rear wheel drive means the more “meat” across the rear axle is a requirement to capably deliver power and handling. 40 is known to be the best all round profile.
I will also tentatively add my understanding of things go like this...
Staggered tyre setups on performance vehicles can help to achieve a desired handling balance. That balance isn’t all about outright grip and performance. They can also encourage a level of predictable handling.
Having smaller width tyres on the front axle generally produces understeer near the handling limit.
A square tyre setup will produce more front end grip when cornering as the front end of the car feels more “planted” due to the greater contact patch.
That said, having never run a square set up I couldn’t advise.
You have an option to run the same size all round, 255 front and rear or 265 front and rear. If you want to run different widths go with a 255 for the front and 265 for the rear although this defeats the object of running a square set up.
A 245 on the front is going to be stretched and a 275 will more than likely balloon.