How to Selectively Nuke & Repave?

I’ve had my site up for years and, over all those years, it’s changed numerous times. Today, it’s a complete cluster; slow, cludgy, irritating. I’d just delete the domain and start completely fresh, BUT I have some stuff I’d really like to keep.

The question is: What are the best practices for something like this? What would your steps be? Anything I should keep in mind?

This isn’t my first rodeo. I’m fairly comfortable with WP at this point. Below is the plan I’ve got in mind, but I’d like a little feedback in case I’m missing anything, ya know?

1. Export all content from domain A.
2. Import all content to sandbox on domain B.
3. Completely wipe domain A (nuke).
4. 100% fresh WP install on domain A (repave).
5. Selectively copy > pasta old content from sandbox over time.

That sound right? Am I missing anything?

Thanks.