Guys I'm looking at running 15x8s on the rear and 15x7s on the front of my Rs can anyone help on what I need to tell the bloke to make them fit properly offset ect ect any help would be awesome

This thread might help..
http://www.classic-ford.org/cfp/tm.aspx?m=53091

It can be done, im rethinking doing it again soon, tho i plan to run a 195 tyre over the 8inch rim which is not to everyones liking, anything from a +20 to a +30 offset 'should' fit under the back of a mk2. tho they are all different and it depends how centred or in an escorts case how off centred your diff is.