So, do I have this correct? You're risking bent valves and poor running over a spark plug socket?
Reminds me of all the old tractors and engines that are put on display at car shows. They are popping and farting and spitting,,,, but they are running !
How can that be ?
The only way to answer your question is to properly check the valve timing, and then see what you may or may not have been missing for 4 years!