Rev Counter Sense Check

[Vista Estate]

Hi Gang,

I've just had to swap out my rev counter on my Mk1 Escort.

I'm running a 1600GT xflow, through a type 2 4speed 1600 sport gearbox into a 3.54 diff.

My rear tyres are 205/60 R13.

I remember seeing a post sometime ago with a cross reference of revs to mph. 

What should I be reading in revs at 50, 60 and 70.

Thanks