double check for a exhast leak very carefully
you can waste time/effort/$$ chasing a lifter ticking with a exhast leak,IMHO
the lifter tick at start up goes away as the oil hits it and pumps back up..
does the oil filter have a drain back valve in it??
are they adjustable rockers??
some will have some movement depending where on the cam lobes things stop at,some open,some closed,some closing,some just opening..ect..
was the engine run in and cam lifters broke in on start up of the new parts??
my guess would be an exhast leak first,then after that is ruled out,look else where for it