Let me start by saying I did as much research into the archives on this subject as I possibly could, and I am still left with questions.  I have a 92 sidekick 2 door with a bum 8 valve motor(bad compression).  I am not mechanically skilled enough to rebuild the motor myself, and the estimates from local shops to perform such a task varies from $2600 to $3500.  I have found a 16 valve low mileage complete engine (intake and exhaust manifolds, distributor, fuel injection, pulleys, cut wiring harness, etc) for around $900.   So am I right to believe that if I got a 16 valve wiring harness, and ecm, that this would work on my sidekick?  Also, how much labor is it to do such a task?  Any help would be greatly appreciated

That seems awful high for an engine rebuild.  Is that with them doing everything from removing the engine, to rebuilding it, to reinstalling it?  If you would remove it and reinstall it, that should save quite a bit of $$$, I would guess.

But if you want to do a 16V swap, you are gonna have to remove the old engine, remove the old wiring harness (the only part of the wiring harness you might be able to leave in place is the part that runs from the drivers kickpanel back to the tail light area), pull the dash (so you can get the old harness out and the new one in).  You also may need the dash cluster from the 16, or possibly have to rewire the cluster plugs, so the wiring is correct.
If any part of the new harness has been cut, or is missing, then you are in for a hell of a job of getting the new engine to work/run.
You need the air intake and airbox too (depending on what year the 16V is, there may be a sensor in the airbox lid).  And there is a sensor that sits between the airbox and air intake tube.
If you are missing any component/sensor, then it can get very expensive to get all the parts required.
It is a pretty labor intensive job, for someone who isn't pretty familiar with how to remove the engine, dash, wiring harness, etc.
I don't mean to discourage you, but I don't want you to think it will be a piece of cake either....because there are a lot of things that can go wrong, if you don't have everything you need and pay attention to what you are doing.

The way I see it is that an engine rebuild is less of a challenge than an engine swap - unless you're swapping in a "fresher" engine of the same type - in which case it becomes a remove & replace type deal.

The way I see it is that an engine rebuild is less of a challenge than an engine swap - unless you're swapping in a "fresher" engine of the same type - in which case it becomes a remove & replace type deal.

Did you do the compression test or did the shop?  I would read up on how to do a leak down and take it to the next step. Try to figure out whats actually bum (head vs block).  Maybe some valves are just out of adjustment or something more simple?

I agree with fordem.  Having just rebuilt my first engine, and swapping that 16v in a sammy... they both take a lot of patience, reading, and above all... interest in doing so and wanting to learn.  If you can follow written directions... you can rebuild that engine (or swap a motor).  There are some variables (what you need done, prices in your area for machine work) that may differ in your case but I spent about $1200 rebuilding my engine with new "everything". Half parts, half machinist.

If you motor swap... by the time you total all the nuts and bolts on top of that $900, you may be about the same price as a rebuild.  Dollar for dollar, I would rather have a 0 mile motor versus a low mile one.  Good luck!

I'll state the obvious (a little late)- try to find a good condition, running 8v and swap them yourself for less than half of what it takes to rebuild yours.

Rebuild yours once it is a spare and improve your wrenching skills. You will need a few special tools, and it will give you time to collect them.

*not aware if 8v's are hard to find