Very very difficult to say as sounds like multiple issues tbh
We just sorted out an engine for someone (which came in for shimming) yet ended up being incorrect titanium valve springs and retainers coupled with incorrect Jun cams which were meant for sr20de with hydraulic lifters.
This causes a lot of valve train noise due to the rate the cams come off their profile & the extra tensile springs cause the valve to slam into the seat and vibrate.
Not suggesting thats whats wrong with yours but removing both the sump pan to access the oil pickup to check for obstructions and also the rocker cover to assess clearances and isdues is the first place to start
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