Lo carb food that will also reduce urine pH?

Norton has been increasing his peeing outside the box recently. Was able to get a specimen and the dip shows a pH of 8. Vet feels he needs to change foods to a "pH balanced food". I have no idea where to even start to find a food that is pH balanced and also low carb. Have been feeding Friskies chicken pate for years.Have contacted Purina and their response is to follow the vets recommendations. Anyone have experience with finding pH levels of foods that are available at other than vet offices?

https://docs.google.com/spreadsheet...Erp5A3aMWPhhxfyGw9LPDbxtzOfdtKYqeRo7I/pubhtml
Norton is aprox 10 years old,diagnosed March 2018, on caninsulin,use accucheck aviva, feed friskies chicken pate occassional problems with mild loose stools, on elavil 5mg bid for peeing outside the litter box.

 

You can add dl-methionine but do not overdue it since if pH is too low/acid then oxalate crystals can form and those can't be dissolved by making the urine more acidic.
https://www.petcoach.co/article/urine-crystals-and-bladder-stones-in-cats-formation-diet-an/

 

Thank you for the info - lots to consider in the link you sent.