Its a dead easy job mate even a novice mechanic can do these.
Had my engine rebuilt a few months ago cost me 1500 quid, when i fired it up for the fist time it was tapping is balls off. Turned out 4 yes 4 of the brand new tappets on the inlet side where fooked! How unlucky is that?So i took them out and the company gave me 4 new ones and i replaced them myself to save time, it was supprisingly easy!