hydraulic lifter noise

The MP P3412068 spring is a pretty high rate spring, and is way overkill for a cam using hyd lifters....... especially with what you get these days for hyd lifters.

The spring chart shows them as:
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They show the rate as 484lbs/in, but the calculated rate based on their data points works out to 462lbs/in.
In any case..... it’s way way more than necessary.
For dual springs, the inner step needs to machined down flush to where the outer spring sits.

A much better match for that cam would be a Comp 995-16, set up at about 1.680” installed height.
It’s a dual as well, so it would also need the step machined on the heads.

The ID of the 995 is pretty small, so the valve guide tops would need to be machined for seals that have a smaller OD.