That is just it. They do.not have the same rolling radius. As the 15's are a 195/50 onto a 7" rim whereas the 13's are a 175/60 onto a 8" rim.

OK, so the 13s give a theoretical installed height of 540.2 mm whereas the 15s give 576 mm, which is 6.6% difference.  Frankly I wouldn't have expected the 15s to be a problem given that it seems to be a pretty standard installation (one I'm going to do myself in fact), so I guess it comes down to your castor settings.
 
Amazing car I must say - very well done.

Its not so much the height that's the problem. I'm sure if I was to fit a narrower 175/50r15 tyre to the 15x7's it would just give me enough clearance to fit.

But yes the castor is the bulk of the issue as it is about triple of what is achieved in std form.

had a play in the car on the weekend. Private skidpan/drift day aimed at beginners.
Took a little bit to get the hang of the car, but after the first exercise id gotta a grip of the car and was starting to enjoy it more and more. 
 
enjoyed it so much brand new tyres at the start of the morning turned into these
 

 
super happy with how the car both ran and handled, with the only issue being how hot the cabin got sitting in the sun all day with the motor running.
 
 
 
 

also still in need of stiffening up the rear end a bit more, should i refit a sway bar in the back or go for stiffer springs. Still picks up inside wheel on full opposite lock.
currently have
 
FOR-024 Kings reverse eye leaf springs
Koni adjustbale shocks- adjustment as per factory.
 
should i try to stiffen up the shocks a few clicks and see if it helps matters or leave them as is and go a more substantial change 

You may have seen this but check out this dudes drift MK2  - http://www.driftworks.com/forum/drift-car-projects-builds/47740-new-mk2-escort-build-reshell-8.html
 
He has gone 4 link, coilovers and a watts link.
 
You know you want to.
 
Cheers,
 
Matt
 
 

dont really want to waste money on doing a 4 link setup in this shell, if i bin it ill have to cut it all out to shell the car, boo. looking at running different leafs or running a sway bar with the shocks clicked up a bit, or just put up with it lifting wheels on full opposite lock, apparently it looks cool. :)

Mish dont really want to waste money on doing a 4 link setup in this shell, if i bin it ill have to cut it all out to shell the car, boo.

What's wrong with your shell? It looks 10 times better than any Mk2 2 door.

its not the straightest shell in the world, the body work isnt the greatest and im sure there is a little rot here and there and the roof is starting to bubble slightly.
 
if i was going to go to the effort of 4 linking with turrets and coil overs it'd be on a much nicer shell, doesnt have to be 2 door.

ratta tat tat

What's wrong with your shell? It looks 10 times better than any Mk2 2 door.

Oh that's sooooo funny (says the owner of a Mk2 two-door)!