Look at my post about my oil pressure problems. I also installed a gauge. Really simple to do! Especially when you get the adapter for your oil filter.
Oil pump/timing chain overhaul/ aftermarket gauge instal
Is the tick upper or lower? If its upper, start with oil psi... Then go to lifters, rocker shafts and camshaft. Make sure you don't go cheap and do just the lifters and rocker shafts and no cam. That's essential. As far as lower engine: rod bearings? Main bearings? What about a slipped liner? Dose it make it all the time when its warm? If so take a video of the tick so we can hear it and help you identify it. HOWEVER rover guys have taken every single moving piece out of these engines, looked at them, replaced them with new, started it up and still have had a tick....
welcome to land rovers!