Scrapping the idea of setting up koha on centos 7 for a moment, might be too difficult, an answer might lie with docker.

Why redo the work when the work is already done? 

Found this docker: QuantumObject/docker-koha

I already have a old database, from I think a koha 3.2 install, Could i use this, with a external volume for the zebradb, external mysql server, and will then koha update my database for me, and use it?