Having recently swapped in a used motor myself, I can say for certain that if your engine is healthy doing the timing belt and water pump makes more sense. I also lost a head gasket at 230k so I would look into getting those done as well. The only thing is that lead times from machine shops are crazy right now so if you want to get your heads cleaned up at a machine shop it might take them 3+ weeks (don't know if that's the case where you are but that's what I was told about 3 months ago).

I did the T-belt and WP myself as my first real engine project, it took me about 5 hours. Make sure you have a very interesting combination of extensions to get the belt tensioner out. Good luck!