Yeah I also have the pleasure of owning several shim/bucket motors. FJ Cruiser, Tacoma (3RZ), BMW K75s, Kawasaki KLR650, 1981 VW diesel. What a PITA. The 1GR is overdue for valve adjustment I'm just dreading tearing into it.
Well, the stupid part is, I have owned several Hilux/mini trucks over the years, and rebuilt several more 22R/22RE's besides, so i should have known better. The effects of old age I guess. Thanks for setting me straight guys.
So I went to the local Toyota dealer where I last had it serviced and asked them to have a listen to give me an opinion but they were insistent on me booking the car in for a proper diagnosis check $150 and didn't even want to walk outside for a quick look and listen. They said they can be noisy and could injectors or fuel line pulsation? They said "A diagnostic check will be $150. Wasn't happy with it but figured since I've been losing sleep over the whole engine tapping thing, I might as well get it checked to get something in writing if they think it's normal. Or if its not normal then what needs to be fixed so I can get it taken care of by the selling dealer while it's still in the warranty.
To get a good idea of the origin of the sound try using a tube. Put your ear at the end of the tube and move the other end around the engine. It really helps with locating the source of the noise. My favorite tube is the cardboard tube for wrapping paper. They are about 30” long and 1” in diameter. Other good option is a piece of PVC pipe used for plumbing. I feel cardboard is safer if you accidently touch any moving parts.
I used to work in a garage owed by my uncles. I have heard lots of engines that sounded like yours that ran strong for a long time. Try to find the source of the noise and fix if possible. Regardless use the truck and enjoy it.