It look's like it's been run on radweld (horrible stuff) which always leaves a speckled residue like that.

Well there are many who spend 2-3 thousand on buying just a chassis with upwards of 5k fitted so I don't see how it couldn't be a good buy. You can get them cheaper but unmolested 3 doors are few and far between.

First and easiest elimination is to unplug your MAF sensor and if it now drives ok that is your problem.

Any sign of a sealer? Some Rolls Royce truck engines didn't have head gaskets back in the day, they used a hylomar sealer which was licensed by RR (can't remember if it was red or blue).

Jeepers that's bad, devastating. Nothing to say that could make you feel any better. Gutted for you.

And hello to you too! https://www.landyzone.co.uk/forum/introduce-yourself.20/

And you are?

I would also disconnect your MAF sensor and see if there is any improvement. This only takes 30 seconds to do with no cost involved. If there is a marked improvement you can leave it unplugged until you have time to replace it.

A ball park idea of the condition would be good!

Hopefully before it lets go and trashes his new rad 😉

Check the bottom crank pulley for delaminating damper, they start clicking when failing.

Have you tried to drive it in reverse for a short distance to loose any transmission wind up?

That would simply indicate a dicky starter motor to me. Cover the basics first.

Do a search for TD5 fuel filter housing: it has a one way duck valve to prevent fuel returning to the tank. Many people have replaced the complete housing to cure their similar problems.

British Leylands Land Rover V8 diesel project iceberg : https://www.aronline.co.uk/engines/project-iceberg/