I would have thought that hired merchant ships would not have seen service after capture, but that was not the case for the ships captured at the Battle of the Gabbard in 1653. What I think is interesting is to look at the ships that survived to the Restoration and past, as they obviously were valued.
Two of the captured ships are listed as 5th Rates in Frank Fox's book, Great Ships: the battlefleet of King Charles II. They were the Half Moon (Halve Maan) and the Rosebush (Rozeboom). Two others were 4th Rates: Mathias (Sint Matheeus) and Elias (same name in both Dutch and English service). The Mathias was a really good ship that came to a bad end in 1667, when she was scuttled during the Dutch raid on the Medway. It says something that she had served for 15 years in the English service, after being captured. Her Dutch dimensions were 144ft x 36ft (unknown depth in hold)(Amsterdam feet of 283mm). The dimensions for the Elias were 132.5ft x 30ft x 13ft. She carried 34 guns: 4-24pdr, 14-12pdr, 10-8pdr, 4-6pdr, and 2-3pdr. The only other ship that we have the Dutch data for is the Rozeboom. The dimensions were 118ft x 27ft x 12.5ft. Her guns were 12-12pdr, 8-8pdr, 6-6pdr, and 2-3pdr.
I keep hoping that documents will surface that will fill in the (big) gaps in our knowledge of Dutch ships during the First Anglo-Dutch War. There is some reason for hope, as Dr. Elias had seen and noted a good number of documents, in the period 1916 to 1930, that I have not yet been able to find (or rather, Rick van Velden had not been able to find). The titles and dates listed in Schetsen uit de Geschiedenis van ons Zeewezen really look promising.