Back in those days the rear wings were held on by bolts, the heads of which can only be accessed by peeling back the upholstery over the wheel arches. These days, they use threaded inserts so that hey can be accessed from underneath.
Your original bolts are going to be knackered anyway, so I recommend grinding the nuts off and drilling new holes for threaded inserts, that way you don't have to disturb the inner wheel arch covering.
The front wings are held by easily accessible nuts and bolts apart from the sections under the body tub, these are also nuts and bolts and likely to be just as knackered as the ones on the rear wings. Again, use threaded inserts when you put the wings back.
When I did this job a few years back my steel wings were very rusty and rather than attempt to restore them I put on a set of fibreglass wings from Sid Watson. Best thing I ever did to the car, Sid got such a good match with the resin colour that I didn't even have to paint them.
