If you aren’t or weren’t happy with your engines power, performance, reliability, etc and whatever before, when it was new, then you aren’t going to be happy with a rebuild. Sorry, it isn’t going to improve what was not there to begin with.

If you liked your engine before the wear and tear took its toll then I would recommend a rebuild. If you have the cash handy and you were in fact happy before hand, buy a new of the same or better and still rebuild the old.

Nothing beats a good spare.