Normally, I'd say avoid, avoid and avoid.
Because you're doing it as a test, I'll give you a few pointers on how to find expired domains, with backlinks.
- There's a website which monitors every single TLD there is, and when domains are about to expire. You can find this website here: https://www.expireddomains.net/ bare in mind, these lists can be very competitive with any domain of value. You're not only competing against other blackhat SEOs, but you're also competing against domain investors. It's a fiercely competitive industry. If you find the dream domain, with the perfect backlink profile, I'd recommend asking NameJet.com's drop catcher to get it for you. It'll increase your chances of success.
- You could buy Expired Domains at auction, there are websites which specialise in this, most notably https://www.domcop.com/
- You could find them yourself with a crawling tool, a popular tool in the expired domain niche is https://domainhuntergatherer.com/ I believe.
I'd like to note that blackhat SEO isn't really my bag. There might be better options, but these are the services I've heard of, and tried (although a long time ago).