[Dsvec]

Hello, I know this thread has been talked to death. But I have a few questions.
I own a 2009 320d e91 (130kW).
I have the car since 2019, I bought the car site unseen. The ad said it had 220000km, when it arrived it had 370000.. that hurt, anyway i talked it out with the seller and he agreed to lower the price even lower and got the car for just 4000€.
Anyway had a few problems in nearly 3 years of ownership, dualmass flywheel, clutch, EGR, and the HFPF the whole lot when it comes to N47 engines, anyway
when I was replacing the HFPF I had the valve cover off and the chain looked okay not too much slack in it (barely any) and the chain rails seemed okay. This was around 40000kms ago.
Last week I started hearing a strange noise coming from the engine bay, and the sound started getting progressively worse/louder, not a rattling sound rather a scraping sound few different shops took a listen and all agreed that its the chain so I will have to bite the bullet and change the chain for a peace of mind.
My dad advised me to check the oil pressure so I connected the oil pressure gauge instead of the oil pressure switch under the oil filter as per BMW manual. When I started the car cold at idle the oil pressure was around 3bar, as it got to the operating temperature it dropped to 1,2bar under load (revving) it maxed out at 3,5 bar..

I am not sure if the pump is dying hence the timing chain issue or maybe the oil pump is clogged with parts of timing chain guide which seems like a common issue. Also when I disconnected the oil pressure sensor I didn't get any warning lights even when performing the measurements.

Since I will be replacing everything on my own I'm looking for advice on what parts or rather what brands do I go for I found a few cheaper timing chain kits with mixed reviews such as FAI are they any good or should I stay away from them. I will most likely go for the more expensive route and buy the FEBI kit and OEM sprockets, I also found a FEBI kit with something called TRITAN coating.. anyone used then are they any good?
Also when I have the engine out it would be a good idea to replace the bearings, and possibly the oil pump.
I found KING connecting rod bearings (supposedly they are OEM).
And for the oil pump can it be tested once out of the car and rebuilt or do I have to go for a new one...

Worth noting that I noticed chain rattling since the last service (last week)when i replaced the belts pulleys, filters and fixed flexible pipe that was leaking on the exhaust and did the DPF delete. I was regular with my oil changes but I missed this one by around 5000km (I usually change the oil and filters every 15000kms). The owner before me used 0w30 while I switched to Castrol 5w30 ll04.

So if you have any advice before I tackle this job please let me know, and advice on the parts I should use.

About the car; it has alot of miles around 450000kms by now.. the dealer wont tell me any service info without the consent of previous owners. From what I can tell the car was very well maintained, everything is original on the car, no missing screws, plastics, interior is clean and everything works, no error codes no lights on the dash. When i was replacing the HPFP i took the injectors for testing, the guy told me that they worked like they were brand new.

Thanks in advance for any suggestions and advice