I think the big end bearings are chattering at 3000rpm

It is hard to say at this range. If a heavy knocking noise that gets louder if you rev up a bit, and it seems to keep time with the engine, you have a failed con-rod (big end) bearing, or less likely, a failed crank main bearing. A lighter knock may be a failed gudgeon pin (small end) bearing. Another possibility is that the engine has eaten a valve or 2.

A blown head gasket can make a noise but it is more like a 'chuff-chuff' sound, like a steam engine.

If the noise has nothing to do with engine revs, look for a loose road wheel or a failed axle bearing, but I doubt it is that.

If you decide it is the engine, the quickest way to investigate is to drain and remove the sump, and look at the big-end bearings. To investigate the valves you could use a borescope, before going to the trouble of removing the cylinder head.

https://cdn0.pissedconsumer.com/review-media/pictures/6d/c4/13869/autozone_denies-valid-warranty-claims-on-newly-installed-water-pump-20130413400428_6dc4-gallery.jpeg

doubt if it would be an oil pump
the copper shavings are more likely to be from rocker shaft /arm bushes
If the bushes have failed then there will be a reduction in oil pressure putting the light on
cam shaft bushes and big end bearing failure is normally a grey metallic in the oil
talk with an accredited shop for a proper diagnosis.

big end bearings( lower engine rod bearings to confuse) knock at idle and get louder with rpm
if the noise changes with rpm and you are hearing it near the ac compressor then it could be the ac pulley bearing
test if it is the compressor by listening and then turning the ac off the pulley will still spin but the compressor stops
if the noise remains , replace the pulley bearings

I always wonder why some mechanics just cant say they dont know.I drive a 2001 century every day with 93,000 miles on it.It developed a ticking noise at 80,000 that i diagnosed as a lifter noise.I change my own oil and I put a quart of auto trans fluid in the engine oil and drove it for a week before i changed the oil and the noise went away and stayed gone.This is a trick I learned from my dad who is also a mechanic and shop owner for 35 years.Give it a try and let me know.Good luck.

might be the valves have been damaged running without oil
- or the crankshaft / camshaft / main bearings
most probably you have to let the engine be rebuilt by a mechanic
(expect cost of more than US$ 2.000)
or get another (used) engine at a scrapyard

first off check your differential fluid in the rear axle make sure it doesnt have metal shavings in it, best way to tell is put your finger in the fill hole on the rear end/pumpkin and get the oil on your fingure if there is any and shine a light on it if its all sparkly then you have a big problem and need to start tearing into the rear end, possible problems...
spider gears, alxe bearings. and also check the U joint for play in the bearings of the U joint on the drive shaft that will sometimes chatter as well.

Yeah its a hydrolic lifter or the big end bearing (hopefully the hydrolic lifter as its much cheaper to fix) does the ticking go away after 5,000 rpm?

it very well can be that depending on the severity of the ticking noise, if it sounds like its coming from the top of the engine, place your hand on it only when you first start it up and if you can feel it knocking slightly and if the noise dies away once warmed up id say its your lifter, if its a heavier knocking rather than a ticking and comes from below or bottom end of engine it may be big end bearing, not good. try putting some engine treatment through the engine oil and make sure you run it in as directions state then change the oil and filter and see if that helps :)

if anything id say it was the bearing