Spring plates and toe adjust?
 

After replacing all my bushings with fresh poly-graphites and a new set of Koni shocks I proudly drove my 75 carrera to the alignment shop. The settings were asked to be:
Front
Toe - 1/16 IN (This will give a solid high speed feel and keep your tires from following every crack in the road)
Camber - .5 degree Negative (Offers good turn in and cornering without excessive wear)
Caster - all the way back (Good high speed stability)

Rear
Toe - 1/8 IN
Camber - 1.0 degrees Negative
Caster - There is no caster setting in the rear

All went well except for the right rear. The shop could not get the toe any closer than 1/4 IN due to some unknown factor in the set-up. We had replaced some worn bolts connecting the spring plate to swing-arm with HD standard bolts that were very tight fitting. Given the minute sensitivity of the settings could these replacement bolts be the problem? The alignment guy said the swing-arm bolt holes were somewhat buggered on that side (perhaps another issue?).

If not an easy fix just how much tire wear does this 1/4 IN Toe on the right side create anyway (or just an extra 1/8 from where we wanted it to be)?

1/4 inch toe on that side will make a difference. 1/4 inch is a lot of toe and will likely cause the car to pull and increase tire wear.

Unless something is bent, there is no reason why that toe shouldn't come into range. Your target settings are very mild and not pushing the range of adjustment.

That some of the bolt holes are buggered indicates that work was performed - perhaps due to something getting bent?