Pleased to read that you have got it sorted Steve
The mileage may very well be genuine, the Pinto camshaft & followers really suffer if the engine does not get regular oil changes.
Stale oil tends to gum up the cam spray bar once the flow of oil is impaired rapid cam wear takes place.
You can get a new cam kit for about £90 but like you say, not a lot of point splashing the cash only to upgrade the engine soon after IVA
