1990 eclipse non turbo blown engine help!

Hi I wonder if anybody can share their thoughts on this.
I have a 1990 eclipse gs 2.0 non turbo.

The waterpump was failing so I had the timing belt changed (with Gates kit) and a new water pump and brought it to a shop my friend recommended.

They changed the timing belt / balance shaft belt / tensioners / water pump, etc.

It ran good for about 1 week, then i heard a "knock" and then the lifters seemed to be clacking loudly.

I had the car towed back to the shop, didnt want to risk driving it more, thinking something was wrong with the job they did possibly. Their diagnosis was 'bad lifters', so they recommended buying and installing 16 new lifters.

I did so, this time though, I sensed a kind of out of balance or "pulsing" in the car, the car was drivable but you could tell it wasn't the same as ("before the lifters were changed" and "right after the lifters were changed").

I drove the car about 3 weeks (less than 300 miles), then the engine just died on me while I was driving. I pulled the valve cover and found a "broken lifter" another lifter was slightly bent and 2 "rockers" were lying loose in the top of the engine, not only that it seems my pistons are shot (at least 1) and the #1 spark plug wouldn't come up, when I finally pulled the plug, there was damage in the spark plug chamber, like something "hit" against the spark plug end inside the engine.

Now, of course my engine is shot.

That sucks because I put a lot of time, money and effort in trying to get the thing right, the water pump failure basically forced me to change the water pump, while I was at it, I thought it made sense to put the new timing belts, tensioners etc...

Any ideas as to what happened?
"something wrong with the job the shop did?"
"poor lifter quality?"
"fair wear and tear?"
"incredibly bad luck?"

I find it hard to believe the work I had done and the fact my engine is now shot shortly (less than 300 miles) after the work was done are not related somehow.

Any ideas?

Thanks.