There is not an image.

You have to use precedent ISO and use git to push 3.0 new stable branch on your system in another folder near from mining folder from 19.2.1.

I had to learn to use git but it is not very complicated.

On the other hand you will have to recompile all the minning software and for my part, the papampi script did not work. It downloads the sources from github, from the dedicated page, but can not properly compile the mining software in stride.

And XMR-Stak seems to be slower once compiled by hand.

I guess it's due to cryptonight v8, but we'd have to see if other mining software is more efficient. Too bad because I appreciate Xmr-Stak which is very stable. I was doing 6.5 KHs, and I lost about 1 to 1.5 KHs. I now have 4.5 to 5KHs :-(
Note that I have not tried to push the overcloking as on the previous version. I realized that paradoxically I was wasting power overclocking and I had a big difference between the pool and the software display. What does not seem to be the case with this new version. Si i will try again to overclock and verify if the pool display the same hashrate with OC. My pool for monero is pool.supportxmr.com. the second in hashrate power.
Note : th tx cost must be lower with this bulleproof and POW hard fork, but i don't verified yet. If someone can confirm, with a tx address, i accept to see it.

I still can not get auto start XMR-stak running with all scripts as it should. For some reasons unknown to me, I was able to launch it by hand yesterday, but not via nvOC scripts.

Another problem, from the system this time, is about DNS resolution. Systemd took control of the name resolution and it works very badly for me. Ubuntu loose more than 10 minutes before finding a normal name resolution.  grrrrrrr
As soon as I put the nameserver in the resolv.conf file everything works fine immediately. Except for every startup, the resolv.conf file is restored by default without the line I added. grrrr
I wonder about the usefulness of having done so in ubuntu 18.04 ...

LukePicci or Papampi
Can you give us back, or remember the links and procedures to install the new version without rewriting a complete image on the disk?

Translated from French with Google translation and not re-read for correction.