It depends on your goals and how your body reacts to what youre taking really.
If your goal is to gain appreciable mass while keeping fat gain in check, i would guess you can get away with (or may need) to eat more than a 500cal surplus. The key i believe is to know what kimd of diet you actually grow on while natural, and add a bit more to this. Then you have to observe what happens to your body and adjust from there.
I have read some accounts of people taking up to 3gms of protein per lbs of body weight, but the vast majority of what i see is 1.5-2gms per lbs.
It's just my second cycle and I'll admit that i still have a lot to learn about my body, but here's what im consuming right now on a cycle of 600test/400EQ:
Calories: between 700-1300 surplus (1000cals surplus on most days)
Protein: 1.5-1.7g/llbs bw
I eat the same stuff almost everyday. Chix breast, brown rice amd evoo.
Hope this helps.
I have gained some fat with this, but not to an unacceptable amount to my standards. I have gainef a considerable amount of muscle, which makes me very very happy with this cycle/diet. Hope this helps.