Moving external DNS server to VPS - eviltoast

I plan to move an external DNS server to a hosted VPS in the near future. I would appreciate advice on VPS specs for this purpose, or an other helpful feedback from others who have done this before. I’ve used a lot of low end boxes to host web services, and would like to do that with this project as well but don’t want to under spec it. It will be used regularly by around 300 users.