Should be pretty easy to distinguish a lifter tick from a manifold leak. A manifold leak will get considerably louder under acceleration and can usually be heard inside the vehicle. A lifter tick will just tick away.
My LR3 ticks a little bit (lifters) and it's audible from beside the right front tire, but it's no big deal. Solid lifters are much louder so these hydraulic ones are just a tap by comparison.
Dave