Excellent find sir. Regarding "Are these speakers still considered good?"...I think you know the answer to that by now. I recently picked up a nice set of M12/90's for cheap that are relatively similar to the L1290's and I love the way they sound.
Regarding the differences between the series I and II, I found the following excerpt in a former post:
"The 1290/2 has a solid state tweeter protection circuit. The midrange driver is a magnetic fluid cooled design with greater power handling capability as a result the two fuses at the binding posts of the original are not present. The binding posts have also been enlarged to accept a heavier gauge wire from 16ga. to 7 ga. I believe the tweeter level switch is present on both models."