Okay Mary, late 60’s is not “older”. I should know. Do know that the majority of the people in the ruin bars will be children. That doesn’t stop me from going from time to time.
Start with the granddaddy of them all, Szimpla Kert https://szimpla.hu/. It really is “typical” and it really is very nice. Kazinczy utca has a number of other, all worth at least looking in the door. If you start at Andrassy ut, walk down
Then you might want to go exploring a bit. Walk east up Wesselényi utca through typical old Budapest to Doboz https://doboz.co.hu/en/home/. It tries to market itself as a bit more upscale than the others, and it is a tiny bit so.
Then head north to Instant-Fogas https://instant-fogas.com/ It’s a huge complex over several floors. Some areas quiet some areas large dance floors like you see in the movies. Always very interesting for the experience. It is near the Klauzál Market Hall and Mazel Tov Restaurant https://mazeltov.hu/ both also worth visiting.
Finally a ruin of a pub witout the tourists; Kisüzem https://www.facebook.com/Kisuzem before heading off the a slightly more mature crowd at Kadarka Wine Bar. http://kadarkawinebar.com/
Here is the list on a map: https://maps.app.goo.gl/wwh2AwKKeHnazN4Z9
Check the websites and go close to opening time if you want to avoid crowds. These places get packed with European Trust Fund Brats after 9pm; but are pretty nice earlier in the day / evening.