I'd find the skip in the vacuum gauge firstly.If you locate and isolate or repair that issue it may or may not be related or causual to the "knock" sound.
Lots of good recommendations and observations I agree with, following my line of thought on diagnosing these issues.
-Agree Compression test should definitely be done on a hot engine.
-If a HOT cranking compression produces #'s that low, I can't imagine it running well or producing the #'s it did on the dyno. a cylinder leakdown test is indeed warranted.(also cam timing can't be off that far and make those dyno #'s), with that I think the compression test data is useless till verified and done under the correct conditions.(make sure the hose seals well if multi part and to s-plug hole..oil the o ring)
Which cylinders/crank pin/s had the problem?[
And full detail of damage. Damaged bearings or broken rods etc. Are the pistons floated or pressed pin pistons in this motor?
If I am following this correctly, the oil pump and shaft swap out was with the wiped dizzy bushing in place. So that testing is irrelevant.
IDK, the drip drip of facts, instead of full disclosure up front of what happened on the original dyno pulls has sent this diagnosis on many unnecessary tangents.
This doesn't make sense to me.. Oil pressure loss, dizzy bushing wiped, oil pump drive shaft contacted block passage unsymmetrical. IDK, seems there is more to the original failure... yet to be disclosed, just the status quo from the beginning
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