best camshaft brand

Yeah can greatly increase chances of success.
before you bolt the top on, paint a white line on each pushrod in a position you can see
slime the lifters and cam lobes with assembly lube.
with the plugs out turn the motor over the correct way with a big breaker
get 20 or 30 revolutions on it
if your pushrods have turned, you know your lifters have turned.
if the lifters have turned no matter how crap they may be they will not hit the lobe repeatedly in the same place, giving the ZDDP a fighting chance of plating on properly and protecting that area of the lifter base that was hit first, for the next time it is hit.
if they don't ever turn, you have a problem, a cam wipe problem. they will wear exceedingly quickly. very quick when new less quick when used...but quick....

if you put in too much ZDDP not only will it plate the lifter base it will plate the sides and the internals.
you will end up with lifters that could stop rotating as much as they did, they are now fatter than they were, in a narrower bore in the block.....
You could end up with lifters that don't pump up as quickly as they should due to the piston and bore inside now being plated, the bore is smaller and the piston is thicker than it was.
1300-1600 PPM is enough and ideally in the oil from the start not an additive bottle that could mess up the chemistry of the rest of the oil.
just get the right oil in the first place pay once not twice.

the bad lifter, bad cam problem is a problem,
but the reporting thereof is polluted with a million and one other things that could cause the issue...but its always crap cam and lifters that get the blame. when you see a report on this, who built the engine, will give you an indication of if it was really a case of crap lifters made from crap material or machined badly. or maybe it was something else

Putting two bottles of ZDDP additive into a 1600 PPM ZDDP oil is not the way....but you may find people who do just that, and then of course they join the masses, who say their failure was caused by crap lifters :)

the ZDDP plating is a chemical reaction you can't stop it, it actually makes surfaces much rougher, removing that roughness each cycle helps the underlying steel to work harden. ZDDP doesn't lubricate at all, think of it like velvet that has its fibres smashed off and replaced time and time gain, the base layer needs to stay in place.

but like spray painting or chrome plating a great fat thick coating just flakes off, too much roughness and not enough proportion of the total of it as a base layer. You need just the right amount laid down in the thinnest of thin layers

Dave