Peter - getting sick of looking for 155/15 and 165/15 tires? Tired of hearing people complain about the limited choices in 185/60/14 when you can only dream of those sizes? I know the feeling.
I've been thinking about a set of 6x14" GTA Campagnolo rims
Take a look at Alfaholics GTA replica wheels - I think they still have the same 'look' as the steel wheels that come on the Duetto, but give you more tire choices. The Cromodora rims are great looking - but somehow I think they suit the coda tronca Spiders better - they somehow have more of a 70s feel to me.
Let us know what you decide - I'm struggling with the same choice myself (only can't afford new wheels this year).