+ve earth rev counter into -ve

[Benspickup]

Im not certain where to get the information for this so i thought i would try on here- I've had in my possession a smiths rev counter that i want to put in my mini pick up as i feel its more in keeping than modern ones- it is however positive earthed but is for a 4 cylinder. Is it easy enough to wire it in for its new -ve earth application? Are there any diagrams avalible? Thanks, Ben

[Benspickup]

Thanks very much- seems simple enough to do. Only thing i am wondering about is the pulse lead. On my rev counter it only has one lead held by a screw, not two as in the diagram