Ok, how I fixed my headlights after stripping the plastic and then cutting out the seized bolts - the pictures tell the story but the assembly is:
an m6 bolt (same size as original, but longer)
a butterfly nut on the bolthead end
followed by a normal nut
The normal nut fits into the remains of the stripped hole in the headlight bucket where the original volvo bolthead was, the butterfly nut is held in place with epoxy putty meaning there's no way the bolt can spin. There is loads of space for the new bolt heads with the butterfly nuts etc attached.
I put the new bolts in place with epoxy putty then bolted the headlight buckets to the car with nothing else in them until the putty set so that the bolts were definitely straight and in the right places. Then I took out the headlights, installed the reflectors with new clips (still available from volvo or there's a place on ebay that sells them) and then installed the glass before reinstalling.
Hope that helps.
Cheers
