Great car. Get used to the attention, a 50 year old design and still one of the best. Much more recognizable than anything else. Biggest problem on a series III is the heat from those 12 cylinders. Cooks the accessories. The 74 had the ignition relocated to a less toasty spot. Do not make any changes that are irreversable. Keep it in factory spec and it should be great. Modification causes problems. Jaguars engineers were a lot smarter than I am. I stick to the original size tires, and if the original radio is still there and works leave it alone. I have two original paint cars that have chips and scratches and some fade but they are the original paint and they are only original once. If you have questions, JCNA has a tech line that is great ,well worth the $60 membership fee ( How much is the FCA ?). I get my parts through SNG Barrett. You are correctm Jags are a lot less expensive than a Ferrari. I had my head (4.2)and transmission rebuilt and a new clutch for for $5000 a third of the cost of a 15000 mile sevice on a 360 ( the one where they pull the engine).
Drive it and enjoy it.