how do I tighten my lifters

This is non adjustable. You have overhead cams and rockers under the cams and in the rockers are lash adjuster (lifters) they are hydrolic and non adjustable. If you are having rocker arm noise then it is replace the lash adjusters. Seal power part number ht2271.

So what you're saying I have to have it rebuilt again and this mechanic had no idea what he doing with this engine

Before you go off on the mechanic, at least tell us what the problem is you're trying to solve. Hydraulic lash adjusters are nearly impossible to test out of the engine and they don't fail very often so most people don't replace them. If some are bad you don't need an entire engine rebuild; you need a simple repair.

If you "know how to work on vehicles pretty good", that would get you by 20 or 30 years ago but mechanics today have to be scientists and engineers. I worked for a very nice Chrysler dealer for ten years, then taught Engine Repair for another nine years, yet that doesn't qualify me to work on the newer stuff. There's just too much changing technology and too many ways I could cause more trouble than I fix.