Thanks to a helpful tip I think we're onto something. Measuring block 093 was -8° crank angle.

What are you trying to achieve?
For the -8 degree you have to mount an adjustable timing belt wheel.
This has nothing todo with your chain or tensioner as long as your wnwi_w value is calm and near 0.

You can buy a new chain if you like but the offset in timing is coming from a recurfacing of block and/or head in the past.
Or from a non-standart sealing which has another thickness.

Obviously this isn't the best way to resolve the problem but I found an additional spring that fits in the cam chain tensioner top piston and the timing issue seems to be greatly improved now. wnwi_w is still higher than 1.5°  after 3800rpm but nowhere near 6-8° like before.

Metal screen was clean when I took out it seemed like it wouldn't cause harm so put back in.
No visible silicone ooze anywhere near the oil hole.
~18k miles on the chain. Both arrows are in the cam keyway grooves when tensioner is tight and loose if that means anything.

Might be relevant, Crank TDC is about 1/8" before the timing cover mark but other than that nothing looked off. Both head and block have been machined.

I should probably take some measurements and make a model in fusion, calculate the forces involved because I suspect the tensioner is still not quite holding the chain apart like it should.
Unless the oil holes in the top piston were just drilled too high or the bore is tapered near the top I don't see a good assurance a replacement tensioner wouldn't do the same thing.

The latter.

Even if cam timing is a 7-8 degrees out, it does not explain the knock and late ignition timing.
Ignition timing does not "move" with the cam somehow, the trigger is on the crankshaft.

Most likely the head was skimmed a lot and wrong thickness head gasket was used together with other issues.

There is never any need to do anything with the tensioner with different springs. But OP seems to be too stingy to fit a new one after an engine build. Not to mention running pulls with 2.5 degrees zwout at high rpm without realizing that the engine is being destroyed.