FWIW, I can offer an opinion as to the cause of ticking lifters but it won't be worth much unless you've just replaced or are about to replace them.
The best prevention that I've found in my 45-odd years of wrenching is to keep CLEAN oil in the motor. So basic, it's overlooked by most folks but I'm convinced that nasty oil (i.e. infrequent oil changes) will clog lifters up to the point that many never recover. Usually, you'll notice the onset of the problem on the first cold morning in the life of the engine, and the problem never goes away.
In most cases, they'll quiet down once they're warmed up, but will knock on startup every day it's cold.
Like I said, FWIW. When I get mine back from the machine shop and start driving it, I'll keep track through the summer and winter and if any noise crops up, I'll post and we can chat some more. (Put my own theory to the test is only fair, ain't it?)
