but I've read on here that the 5 cyl. diesel (just the engine) is about 450 lbs, and the auto trans is around 175. I know the manual trans is a lot lighter than the auto. I would think the 4 cyl. would be a little more than 4/5 the weight of the 5.

No guarantee on any of these numbers.

On edit:

If I had all that stuff, I think I'd leave the flatmotor in the Ford and assemble a turbo 5-cylinder/4spd '79 240 (assuming you aren't parting it because it's in "parts car" condition).

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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.