Image caption from an interview with the frame builder for the original photo:

White Industries custom six-bolt crank for integrated bottom bracket disc brake- built when track bike riders were being ticketed for riding on the street without a brake.

The most issue you’ll have is with all the different standards. Check these areas:

• bottom bracket (probably 67mm BSA threaded)
• rear axle (135mm quick release?)
• disc brake mounts (I think these changed the most since)

I’d convert it to a 2x9 setup. Probably mostly used parts. A Hollowtech 2 crank with somethin around 32 / 38 compact chainrings. Buy a complete 9s wheel. For disc brakes anything hydraulic would work as long as its not too powerful, I think 180mm rotors might bend the fork noticeably.

If you are interested in learning to work on bikes I think this is a cool project. Otherwise a newer used bike is cheaper and less time

As a hungarian, wholeheartedly fuck orban and his ghouls. I’m ashamed of our nation