Rickshaw, I have to agree with you. When I saw the rego on the Veltro II I chuckled. With the MB.339, Aermacchi has shown a definite "touch" with registrations (all the early prototypes had registrations that were differently languages words for "nine").
BTW, the MB.339K looks to have the same cannon fit and bulges as the MB.326K, you might consider starting with those two to kit-bash a MB.339K.
One decal set I wish was available was for the MB.326D which was a small run of conversion trainers for Alitalia and flew in a version of their standard markings of the period. They were later transferred to the AMI when they'd served their role with the airline. If it's not asking too much, I'll take such a set in either 1/48 or 1/72 or both.