It would almost certainly be cheaper to replace that engine than rebuild it.
The good news is that KLZE replacements are cheap(ish) and more powerful.
For example: https://www.enginesus.com/product/kl...-93-mazda-mx6/
Your 1992 car (I think that means you are in Australia?) would be equivalent to a US 1993 model. It's a direct fit.
Edit: I see from your other posts you are in the UK not Australia. No matter. The Japanese Domestic Market KLZE will be a direct fit in any case.