An injector would definitely be the best first guess. But if the ticking continues regardless of injectors being disabled one by one, it also could be a failed cam follower (lifter).
Your engine is probably a late '80s or early '90s unit? So it would have the hydraulic self-adjusting lifters if so, unlike the solid mechanical shim adjusted lifters we have on the older early '80s US model engines here. The switchover to hydraulic valvetrain occurred in 1987 as best I remember.
The hydraulic lifters are a nice feature since they never need adjustment, BUT they can wear out with high miles and sometimes can suffer failures of the follower surface. See this thread that links pictures of how this can happen, on a slightly different but highly similar engine that uses the identical hydraulic lifters.
https://d24t.com/showthread.php?t=2147
Since you did the first test of cracking injectors open to check them and didn't find the issue that way, I think the next step I would try is removing the valve cover and taking a close look at each camshaft lobe and each follower. Probably have to turn the engine over with a wrench a few times to see them all. Look for issues/damage like what the photos above show, OR for a lifter that looks OK in terms of its surface but doesn't seem to be holding pressure and is sitting visibly low in its bore even when the cam lobe is not in contact with it. Some people also like to gently press down or lever down on the lifters using some kind of soft tool (plastic) to check their function. They have internal seals and a piston that can wear out and fail to achieve full valve lift and timing, causing a miss and noise like what you're seeing.
Valve cover removal on your intercooled engine is a little more involved since you have to take the intake manifold extension off, but not bad otherwise.
Welcome to the board!
Sharp looking wagon you have there.