Hi I am new to this so please bare with me.
I have recently purchased a 1989 Chevy cavalier z24. The engine is a 2.8l C6 but it is bad and worn out. I have been looking for options on a swap I found a 3100 from a 1999 Monte Carlo will this work?

Your will have wiring harness and PCM problems, and then the PCM will be incompatible with that '89 tranny....the PCM will be OBD II, and that is an OBD I tranny....

So it would be best to get an engine from The exact same car

That would be the easiest solution, like plug and play.....

It would be ok if you install an OBD I engine, to have less problems......however you still need a new engine harness and ECM.....

But this is a 28 year old vehicle, and is not worth the effort, unless you have money to blow, and have some sentimental attachment to the vehicle...

I think I will continue to search for a 2.8l from an OBD1 vehicle because my car has the badging for the 2.8l and I would like to keep it some what original. I would like tips on how to increase it'*​ horse power on a budget of course. Any suggestions?

There is no such thing as horsepower upgrades on a budget. Especially on a 28 year old car. Sure some would suggest CAI, better spark plugs etc, but those won't have any effect on the butt dyno.

Thank you and I am well aware of the vehicles age which is why I won't get rid of it.
I also understand that on a budget doesn't mean free or close to it especially when it comes to automotive parts.
I am thankful for your help and opinions. However I believe I will continue with my research from a more positive outlet
Thank you.

I have done some digging around on the interwebbs, and it suggests that, cammed with about $2k worth of engine mods, the engine stuggles to put down 155-165 hp, 30 more than stock. I feel like the cost does not meet the benefits at that level. I haven't looked at forced induction however.

What many have done however is swap in a 3400 or a 3500 engine. If you can source a wrecked fleet vehicle as a donor, you can drop in 200hp right off the bat. Admittedly, it will take some fab work, and sorting out some things, but the internet seems to be full of others that have gone down that path.

However, it looks like airflow is a big impediment in the 2.8, so getting a cam and better valve train in is a must.