Its extremely unlikely that the head or cover is warped, so you can allay your fears over that. What is more likely is that the rocker itself is eithe worn, or the valve/guide is. But that would only yield a mild issue when running. If your bike is not felling "tight and tuned" then a good tune-up and carb synch should help the most.
You have to bear in mind, its 35+ year old bike. They will have good days and bad. And ownership means taking on a few projects outside your comfort zone. You won't blow anything up, so don't fear undertaking these things with a good manual, some pictures, and posing a few questions here.
If I lived near enough by, I'd come up, tune you up, and spank you for being a scaredy-cat
But seriously, you can do this stuff. Follow the recommendations made, don't presume failure or devastation before its done, and go slowly. We are all here (virtually) to support you.