If they were RL-7000s they had a very high efficiency 93 dB and would work with almost any receiver.
And BANG & OLUFSEN made and still makes excellent speakers. P.S. they also made the leading turntable
However, they are almost 40 years old. material ages and becomes brittle, electronics degrade. I would hate to see a person get some good vintage speakers and then have them fail shortly after aquisition.
I would look at some newer speakers. If $250 is your price range then Joe Schmoe is right the Cambridge Audio S30 are excellent speakers. If you were just looking for a pbargin and $250 is not your price limt then there are other options. How much would you be willing to spend for good speakers?
Good Luck!