the V8 ratios aren't the same.
I seriously don't remember what RPM's my Esprit runs in any gears... but LEW knows
Esprit Models
Ratios: Gear Ratio km/h/1000rpm
5th 0.82:1 37.2
4th 1.03:1 29.6
3rd 1.38:1 22.0
2nd 2.05:1 14.9
1st 3.36:1 9.0
so the math works out to 2379rpm at 55 in 5th
and 3029rpm at 70 in 5th