The thread below shows the roof being taken off my new shell and being replaced with a non sunroof skin.
It's quite a simple procedure, un pick your donor roof from the internal side so that it leaves an un-holed 'new' old panel, ie drill the spot welds from the rear and avoid puncturing the flange of the roof skin.
Do the reverse on the roof you are removing, drill out the spot welds through the skin but don't puncture the internal rood structure.
Swap over the skins and spot weld back on after cleaning and treating all mating surfaces.
If you don't have access to a spot welder you will have to drill and plug weld, not sure if some of the new bodyshop adhesives would be enough on their own to hold a skin on.
Cheers, Paul
http://www.forum.triumphtr7.com/topic.a ... C_ID=11433