I haven't run the same size front & rear for about 30 years.
My driving involves a lot of longer distance highway mileage, so I usually go for something with a larger diameter than stock on the rear to give me some taller overall gearing. This often corrects the speedo error as well.
I have never bothered to rotate tyres either & I have never seen a demonstrated advantage with this practice.

For the front I will run something with a stock diameter or a little smaller if the front has been lowered to help ensure that there is adequate clearance when turning the wheels on full lock.

Both my 1000 sedan & my current 1200 coupe ran/run 185x60x13 on the front. This is pretty much equal to the 1000's original 5.50x12 cross ply & the 1200's 155R12 radial ply optional tyre.

For the rears I used 205x60x13's & these are within 2mm of the 1200's stock 600x12 cross ply tyre size. The rubber 'rake' that this produces also gives the car a little 'attitude' which looks good to me.