Radiator Leak

I have a coolant leak at the neck of the radiator on my 2001 DB7. My mechanic tried a high end epoxy but didnt work. No new (or used) radiators presently available (Part #32-121574-AD). This radiator is also used in some V8 Vantages and I believe DBS. What about Radtec or other universals that say they are compatible? Any ideas are appreciated. Thanks, Dean