UK Car Repair: Wheel Arch Repair, jaguar e type, rear wheel arch

Question
I have a 1974 Jaguar E-type with rust problems.  I'm a novice at body work with a lot of patience.  The rear wheel arch edges have rust rot.  I have replacement panels but am unsure how to install them.  Do I use a butt joint or do I flange the original skin edge and tack the repair panel on top?  After welding up I plan to lead the joint instead of using "Bondo".  After looking at the inner and outer wheel panels I'm of the impression to butt weld the inner panel and flange weld the outer.  Is this the proper and accepted method.  Thanks for the help.  Can't seem to find good body men any more.  All the shops want to do is insurance work.

Answer
Being in California for the last 30 years has not improved my knowledge of rust repairs.  Actually we have a 4.2 Conv we are putting new floors in at this very moment.  You have the right plan and with your attitude, I think you will do a very good job. By the way, who did you buy the panels from -normally they will give you tips on fitting as there are several designs. Merry Christmas