Mark, if you are going to glue, investigate ductseal SB (for solvent based) available from Parchem in Bentley (about $6 a tube). It is designed/used for sealing and fixing airconditioning ducting but is also used in Landscaping for sticking paving onto pool headers and steps (and anything else that needs sticking or you break whilst on site
), it has some elasticity but is as strong as all hell. I would spray a panel of that donor car you have and try it on that first, to make sure it works and doesn't react badly with the paint.
Cautionary note, don't leave tubes anywhere warm like in your car, the stuff swells up and pops the plunger out the end of the tube and makes a hell of a mess.
Cheers,
Mike