If you want to do the whole series of A-4s the old Lindberg kit, in 1/48th scale, is a model of the A4D-1. It is more like the proto-type A4D and would require a lot of work to make into a nice model, but it least would give you a starting point.
I'm sure it is still being produced as the Lindberg folks are like the Energiser bunny when it comes to producing their old kits.
As a side note the Hasagawa series of A-4s will include an A-4 M, due to be released this summer. We will finally get a 1/48th scale A4 M ! (a good one that is - Hobbycrafts does not count)