On MK1s the rear springs have been known to break...Mk2 springs are available.
The heater hose is a known weak spot and can go 'pop'...a strengthened one is available from the 260s shop.
Occasionally people have had problems with radiators failing so check carefully!
The heater valve is poor... a better one is available for 260s members from Black Olive, here and on the 260s site.
(Please add to this....it was just to make a start! )