Lifters aren't that porous. Soaking for a couple of weeks is not really necessary in terms of preparing them - but it won't hurt, either. Depressing them repeatedly while upright in a can of oil will bleed out air, but leave stored in oil then until fitted.
The spring inside lifters is enough to "recover" with only the dead weight of a pushrod on it, even if the lifter is empty of fluid.
If everything is new, then all adjustments for inlet will be near-identical, and all exhaust settings nearly the same as each other. Cam base circle may vary slightly between inlet and exhaust, so don't worry about minor cross-differences.
A lifter has about 120 thou of "tolerance" in its adjustment; you want to be on the light to middling side of that amount.
With just the dead weight of a pushrod sitting on the lifter (engine at appropriate cycle timing for setting rockers), try gently jiggling the lifter up and down. It will feel tacky from the assembly lube but movement will be noticeable as it goes from metal-metal contact to free, and back again.
Small incremental adjustments are needed until this jiggling no longer results in the pushrod leaving the lifter "socket". Now add no more than 360° of adjuster.
Measure the underhead clearance of the rocker ajuster to rocker arm, and replicate on other cylinders. That should wrap it up for you.
Regards, Adam.
