As a retirement occupation I specialised in XJS second-user Jaguar parts, grubbed and logged from good-quality cars. Also, to a lesser extent, parts from late Jaguar XJ40, XJ12, & X300 models of the 1990's.
XJSstuff still has thousands of used spares, catalogued on computer by Jaguar part number, and so remains a useful source for obsolete and hard-to-find XJ-S used parts. I do not have a yard or donor cars to pick over, but operate on an email/mail-order basis.
Although I am in the process of running down stocks and closing the business, it will be worth enquiring about your requirements for some time to come.