Carol I've been thinking a lot about Murphy ever since I saw your post earlier today ... And noting that he'd been dx'd with hepatic lipidosis back in 2011, I'm thinking you may be spot-on about this; his liver may not be handling the fats in canned foods well at all.
So ... a question (which may seem a dumb question if you've already tried this, but here goes): Have you ever tried roasting a whole chicken in a crock-pot (remove the skin first), then tearing it apart and grinding it up in a food processor (basically making it into a pate)? I know you'd need to add both taurine and arginine (amino acids that are essential for cats). But the reason I'm mentioning this is because - when our dog had liver cancer - I learned that plain chicken is
far easier on the liver - and easier on the digestive tract in general. (So I was roasting a whole chicken for her every week, and putting it into the freezer in single-portion containers. She lived a very good quality of life for a full year, despite the terminal cancer, on this diet, along with a couple of supplements she needed - the vet was astounded.)
You've probably already seen everything there is to read about hepatic lipidosis, but I read an interesting article about it today - so have attached it here in pdf format, just in case it might help a little (specifically re: amounts of the amino acid supplements needed if you were to make food for him yourself).