I like the 5.0 idea, but it sort of depends what year you're talking about. It sounds like the one you can get is an early 80's or late 70's model with little more power than the stock M110. If you can get a later model HO 5.0, that would provide lots of power for a 114. Another thing to consider is swapping the HO (or aftermarket) cam and heads onto the older motor.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.