Sorry William would not eat the canned alone, but happy you have found a diet combination that works. My dog would always eat the prescription canned even if sick, but all dogs are different. A few weeks on the low fat canned cleared up my dog's P issues and the value came down to 93, then soon after to 63.
If he appears a little picky still and the cPL number is still greater than 400, could it be he still has mild Pancreatitis! My dog had P symptoms with a value of 399.
Perhaps a Snap cPL test at the vet might check whether he is totally better?
Good to hear he is doing well and hope he is over the P.
Thanks for the update