1989 ranger xlt bad tick almost knock at 3k rpm

[1989rangerdanger]

i have a 1989 ranger with a 2.9 and 5 speed owned it 5 years always ticked but now when i get on it around 3k rpm it get worse and almost sounds like a knock will do it when i downshift as well truck has 160k on it think its cam bearings. would it be easier to pull the heads off and replace the rods,rocker arm,bearings,valves,valves springs,and lifters or build another motor tried all magic mechanics in a bottle dont work but for a week