It is very hard to think of possible rivals for the Coupé and Convertible models, these cars created a class of their own when introduced. Their mix of elegant looks, comfort and sporting abilities proved to be an unique mix which not many other cars could compete with.

Therefore you can only find a couple of cars who could be seen as a competitor, if these cars were seen as real competitors in the 1960s remains a guess to me.

Jaguar E-type
(model 1961-1964)

Aston Martin
(model 1958-1963)