But if you try to get the freelancer from freelancer.com or upwork.com then you could be able to reach the perfect candidate. I think if you do not yet get a good/perfect candidate then please have a try on the freelancer.com or upwork.com
Would be pretty hard to find someone on those freelancer websites, coding a mining pool is a very "specific" field, it's not enough to be an excellent programmer to write a whole mining pool up and running in a reasonable time, it is doable, but the research time alone is going to cost OP way too much, it would be better to post this in the mining section and/or on mining telegram groups.
People like CK and Kano have some solid pools running, with the majority of the pool code being open-source (but outdated), it would be a lot better and probably cheaper to just hire people like them because that
1- You get a mining pool made by someone else who has a mining pool running for years (nearly zero bugs in production)
2- They have the code ready, with just a few modifications you could have it up and running (way less time than being done by someone else with no background).