I scored 1200 odd for 2 on medium, one player scored over 600 runs.
It was against Zimbabwe.
But your right, the game crashes periodically once you get near 700.
Here are the batting stats for that innings. I cheated a bit tho because they were custom players. Still, it proves you can get over 1000 runs.
On the other hand has anyone taken a 10 for? I did it on an England short tour, I took a 10 for three times, one of them was 10/0. It was only first class though.
Unfortunately, my game records haven't picked it up as the best innings performance it still says 7/73 is the best even though it says I have taken 3 10 fors.