Were the ring gaps equally split around the circumference. Is there some black marks in the cylinder pic running down Have you honed the bores after new rings

Not sure but you’d get a very tight hub nut 😀

Was small ends on pistons checked

I would think if you have checked everything while engine out and all looks fine then reinstall, but was there a question over gearbox noise , so take gb off mounts and prop and move back so engine can run disengaged from gb and if quiet you know gb issue

Agree lynall , I kept series 3 exhaust but mines a di, does that downpipe fit to the S3 manifold or the tdi manifold Some info here from 300, https://www.landyzone.co.uk/land-rover/exhaust-200tdi-series-3.298508/

almost Same one imperial one metric , nigh enough for pitwork as the saying goes

result https://www.landyzone.co.uk/land-rover/tappet-assemblies.356475/

Just reading back through the posts , when it was running did you try it with fan belt removed to isolate any bearing probs on water pump / alternator , loose pulley wheels 🙁

if anything should be anti friction like teflon but not seen any online. (will have a google) i can see EW on them whats on other side

this is the worn rocker i replaced with new on mine but didn't make any real noise, maybe time to check the valve springs make sure they not broke and sit at correct height as in manual. guess youre quite sure you have adjusted each rocker to 10thou clearance using rule of nine. anf youve not...

once you get started there's no stopping you! the rollers look good from what i can see , should all be highly polished with no flat spots, those tappet slides should be clean brass all over not covered in black deposits, did they move ok in the slots both roller and tappet need to be set one...

Oops thought it was oil pump, but try with oil pump skew gear and dizzy out first, On the rollers you can get flat spots but not as Loud as your knock more a tap But knock is twice as fast as a single valve operating unless it’s banging top and bottom

That’s a well thought out test, and you found the knock with dizzy in and lift pump , so keep going and remove ancillaries one at a time , ( lift pump lever on wrong side of cam poss) until sound stops, as you’re in so deep now not far from head removal then you can remove and inspect rollers...

Or back off adjuster fully check pushrod in cup and slider not broke