Correct fan shrouds for early A's are not the easiest to find - that's because I was told I hoard the 4 I have! :D To make the shroud work correctly with the 65/66 radiator, you also need the correct mounting brackets. I'll drop you a PM about it.
It would be helpful to know when it's overheating - driving along the highway at speed or low speed driving or ?
Also, welcome to FABO!