Remember that half the point was that even if you could (hypothetically) make the Zetec or CVH reach 8000rpm, you still need a SHIT LOAD of power to accelerate fast enough to get to 8000rpm in SIXTH gear. It's all a balance, lots of power will fuck the early part up as you'll struggle for grip. However, if you run wide/sticky tyres to give the early grip, they will have too much drag, which will affect the speed.
There is SO SO much to this.