trying to get Modular Bosses to run on a "new" PC

Hi all! I very much understand 'Some Old installers currently do not work, Use latest for your version' :-) I am hoping someone can help me. My son, who is very young, is big into Minecraft and mods - he has blown me away on how good he is, he can hold his own against me and my videogame buddy who are both about 10x older than him. Anyways, he is dying to play against the giant sandworm, which I know is a part of Modular Bosses, and AFAIK is not part of any other mod packs. He saw it on youtube.

It looks like MB runs only on 1.8.0, and not 1.8.9.  1.8.0 being one of the old ones that isn't working. I found gummby8, who made MB on reddit and they were kind enough to reply, I asked if they knew of any way to get it going and they did not.

I told my kid I'd ask some more people online, so that's why Im here asking. Any help would be greatly appreciated!