The NRP Diogo Cão, was added to the Portuguese Navy in 1957. It was a John C. Butler class DE, ex-USS Formoe DE-509. When she was delivered to Portugal under the Mutual Defense Assistance Program, she already had suffered an upgrade by the USN, but in the next year, both ships (with NRP Corte Real F-334,  Ex-USS McCoy Reynolds (DE-440)) went on a heavy refit in Arsenal da Marinha (Navy Arsenal), mainly on electronic equipment, being the most visible change on the mast (compare with the 1957-8 real ship photo). Both ships were sold to scrap in 1968, being replaced by Almirante Pereira da Silva Class frigates (US Dealey Class) >From this ships, there is one of the 5'' guns in the Museu de Marinha, but in a place not accessible to the public. 
The model: For this project I have used the PitRoad/Skywave W17 USS John C. Butler model, which, by the way, comes with two models in the box, allowing me to keep the other to make the NRP Corte Real F-334 in the earlier configuration. As references, I have used the following publications: - Two part article by Ricardo Matias (the same modeler who had written the article that allowed me to scratch built the NRP Alvares Cabral), issues #801 and #802 of Revista da Marinha; - 75 Anos no Mar (1910-1985) Volume Nº6 book; - Marinha Portuguesa 1962 book;
And my own photo archive and also, as usual with portuguese navy projects, a trip to Arquivo Central de Marinha (Navy C,entral Archives) were I have requested the copy of 4 photos, which, because of rights, I cannot publish (I could but for publishing I would have to pay more - so, my apologies on being honest here).
With all the information gathered, I started by the obvious: the hull. Here all I needed to do was to correct some sink holes and I had the base for the new project ready. Since the model comes in the WWII configuration, I had to remove all the 20mm Oerlikons stations, Torpedo tubes locations, remade some of the upper decks, make new twin and quadruple 40mm Bofors gun tubs (I used L'arsenal quad tub as a basis, since it was not the same type). Also the gun directors tubs were scratchbuilt using plastic. The most difficult tsk was scratchbuilding the characteristic new mast, for which I used brass rods and plastic card (for the platforms). The radar screens come from several GMM and Tom's sets. Also have used Tom's Modelworks DE Pet set, but since I have used this set before for USS Cassin, I had two depth charge throwers missing (a new set is ordered and waiting for it to apply these parts). All the guns were replaced by resin articles (see list bellow). Also a noticeable feature on these ships were the quad fire control radar dish, which was also scratchbuilt using PE left overs. To get all the features, the photos were very important and valuable.
Painting it: The painting scheme is very simple: dark grey on decks and portuguese navy light grey/green for vertical surfaces (exception made to the top of the bridge). For the dark grey, I have used a Mr. Color paint which is very similar to the Portuguese Navy one. The Light Gray/Green is the original navy paint. This time (as opposed to the Alvares Cabral project) I have used less light grey to scale down the color and this time I think I have hit the right shade of it! Of course this was much thinned, so that it could have been airbrushed.
Next was applying the homemade decals (no company makes Portuguese Navy decals, in any scale). A coat of flat varnish and this was almost done. Rigging was made with Caennis line (courtesy of David Griffith!) and placing the national flag and the Romeu callsign (indicating that the ship is on SAR mission) and that's it.
The sea base is my usual (one of the two, actually) procedure with Das Pronto modeling paste, painting the trail of another ship to make it more interesting. It was a fun project, over three months of work 

Boxed Items:
- Skywave/PitRoad John C. Butler Class DE box;
- L'Arsenal Quad 40mm Bofors resin set (mine was missing the PE parts);
- Niko Models Double 40mm Bofors resin set;
- Tom's Modelworks DE Pe set;
- Midship Models Armament sprue (for directors and ships boat);
- Tauro Models paper flags (Romeo callsign flag);
- Various bits and pieces from the spare box (Radar screens); - Eduard 1/700 figurines;
- Rigging is Caennis Line.

Scratchbuilt Items:
- Mast with brass rods and Evergreen;
- Gun Tubs and Director Tubs with Evergreen/Plastic;
- Quad parabolic radar screen and support; 
- Seascape is Das Pronto Modeling paste with my usual method;
- Homemade decals and National Flag.

Cheers, Rui