As the title mentions I've got a 91 Civic Si that misfires at idle and low compression on one cylinder.

Earlier this month my car broke down out of state. I was going down the highway at 70mph and had a total loss of power, engine would crank but wouldn't start and would backfire as well. Then I had it towed to a shop in the area. They discovered that it had jumped timing and that there was about an inch of oil in the sparkplug holes. Valve cover gasket, sparkplugs, and sparkplug tubes were replaced. I had assumed the worst and guess that either the valves were bent or the engine was total junk. The next week I brought it back home and took it to another shop to have it properly diagnosed. At this shop they discovered that one of the screws in the distributor was missing and replaced the cheapo sparkplugs the previous shop put in. Today I picked up the car and came to find out that there's a misfire pretty frequently at idle, engine doesn't die just bogs down and makes it scary to sit at a red light. The shop found that there was no apparent damage to the engine when it did jump timing and cylinder 3 had marginally lower compression compared to the rest.

It's got a D16ZC running in it right now, I doubt that's the original engines but ZCs and A6s seem to be hard to find. I'm just lost as to what action to take at the moment. Would a rebuild of the head be worth the time and money?