Have I identified the IUPAC name of this ketone correctly?
Your assessment is correct. According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), the order of seniority of classes in decreasing order of seniority is as follows.


  (…)
  16. Ketones
  17. Hydroxy compounds (includes alcohols)
  (…)  


However, locants are placed immediately in front of the part of the name to which they refer. Therefore, the correct name for the compound that is given in the question is 1-hydroxy-4-methylpentan-3-one.