Forgive me if i'm wrong or off, as I don't know that much about the 370z, 
but with my napkin math, I get these results.

- 7500 redline
- 18" Rear Tire Size (non-sport): 245/45WR18
- 19" Rear Tire Size (sport): 275/35WR19
- 19" Rear Tire Size (Nismo): 285/35YR19
- Gear Ratios:
      6MT         7AT
1st:  3.794       4.924
2nd:  2.324       3.194
3rd:  1.624       2.043
4th:  1.271       1.412
5th:  1.000       1.000
6th:  0.794       0.862
7th:  N/A         0.771
FD:   3.692       3.357



Gear      6MT/6MT Sport      Nismo       7AT
1st               41mph      42mph     35mph
2nd               68mph      68mph     54mph
3rd               97mph      98mph     85mph
4th              124mph     125mph    122mph
5th              157mph     159mph    173mph
6th              198mph     200mph    200mph
7th                 N/A        N/A    230mph (229mph for sport)