I would first do a detailed cleaning of the rifle. You have to determine the exact builder and model of the Pattern 14. Not all Pattern 14 bolts fit other Pattern 14 manufacturers and even within manufacturers. For example I believe your rifle is probably a Eddystone built rifle judging from the stock. A bolt from an early Pattern 14 MKI will fit a later Pattern 14 MKI* but a later Pattern 14 MKI* bolt will not fit an early Pattern 14 MKI due to the larger locking lugs on the Pattern 14 MKI* bolt. The one bright side is all of crud on the rifle probably protected the finish and bore. Good luck on your find.