lifter change-hours labour??

[LEOMAC23]

Hey does anyone know how many hours labour is involved for a mechanic to change my lifters (getting really noisy)and is there any other parts it would be worth while changing when he is at it,like pushrods and stuff. Also does it sound right for a lifter to be getting noisy on a 97 with only 65000mi on it, its a loud(not that loud but noticable when you open the door) tick,tick,tick noise that gets louder with the engine and louder when hot,is there somthing else that could cause this beside an exhaust leak?? Thanks to this site and everyone here for all the help!!