Strangely, the one pushrod that I see turning much slower is cylinder 4 exhaust. It seems to turn - but very slow. But, there has been really no noise from cyl 2-4-6-8. Most of the clacking/tapping noise was from driver's cylinders (primarily 1 and 3, it seems). The pushrods on cylinder 1 and cylinder 3 and all others (other than cyl 4 exhaust) appear to be spinning pretty fast.
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There was very little to no noise on the last start from any cylinder. Cyl 5 (which had intermittent - larger spurts of oil out pushrod) seemed much better.
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So I guess the diagnosis could be sticky lifers / maybe some internal grit/sludge is getting into lifters (or was in the lifters?). The sticky lifters / grit then causes the intermittent issues I am seeing ? Like intermittent clacking-tapping/slower spinning pushrod/intermittent larger spurts of oil from one pushrod. Perhaps, the marvel mystery oil and seafoam I added has helped dissolve or clean the lifters a bit and this made the issue better (or more intermittent?).
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It sounds like the best approach is to pull intake and inspect the cam lobes/lifters/pushrods/rockers and drain oil and check oil filter pleats
