Range Rover L322 ENGINE PROBLEMS

Hi Everyone
I am new to the site I have a Land Rover TD5 and my Range Rover L322.
my 2003 Lr322, it is a petrol 4.4 V8 Bmw engine, and am getting a bad noise comming from the engine, started as grating sound then progressed to Tappet, changed the oil and filter, but has not helped the engine has 96k miles, it sounds like timing chain issue, the old oil filter had very fine filings of metal in it ? very worryin, would I been safe to get simply timing chain rplaced ? I need to repair as economically as possible, not sure of the damage or indeed of a trustworthy garage to administer the works, does it sound like the whole engine should be replaced ?? swap out for a recon or at worst used ?
Any suggestions would be really appreciated don't want to have to loose her, but at the same time need a solution.
I thank anybody in advance for any input and guidence and look forward to all aspects of this forum and site, I hope to be a good contributer as well as hope to get some questions answered.

The lifters can be noisy, and so can the vanos on this engine. A good hard run after a correct oil and filter change can help, but I suspect this may be more serious.

I've seen the small end bearings cause problems. What's the history on the car in terms of service and condition? Has it ever had overheating problems or periods where servicing hasn't been carried out?

The cost to rebuild the engine is likely to be more than finding a second hand unit, or even a reconditioned unit. There is about £600 of SPX service tools required to do just the head work on this engine, however, I think there are generic BMW tools available from Sealey for the M61 and M62 engines. What I'm trying to say is that most independent probably won't have this equipment and will have to factor this all into the cost to rebuild your engine. IIRC, you are looking at 10K for the engine from Land Rover so maybe look for a BMW source. The M61 is similar to the M62 except that the M62 is a drive by wire version of the M61.

metal filings in the filter are as serious as it gets, engine needs to be removed and stripped to ascertain the problem as a early fix could save the cylinder bores from damage as they are Aluseal and are very expensive, if you need any advice drop me a line !