My guess is they don't stack up great in modern terms. They'll play loud on not much power and wouldn't terrible for the time. Hardly unlistenable. Power them up and listen to them.
Looking at the link, Klipsch quotes the bass extension as 32hz, and given the response graph in it I'd say that these are pretty good, even for today's standards.
Yes, they will have the "Klipsch sound" (recessed midrange), but given their sensitivity and power handling, they should sound pretty good since they can actually get loud, unlike a lot of modern stuff, and you can easily fix the elevated treble with EQ,
(That's all assuming that nothing is broken.)
My recommendation would be to hook them up to a decent amp, and take a listen.
In comparison to the SVS Ultra Tower (Though it has been established that the SVS speakers aren't exactly the best, though they do make good subs):
The Fortes use a horn loaded midrange and tweeter, which, given Klipsch's reputation and experience, is probably in line with the SVS tower's midrange / tweeter array performance, or at least close to it. (I am basing this off the fact that the horns will handle more power, and hence dynamics will be better, but the old horns will have distortion issues that the modern drivers shouldn't have.)
The Fortes use a single 12" bass driver with a 15" passive radiator. The active driver area is about 113 sq-in.
The SVS towers use 2x 8" bass drivers, with a port. The active driver area is about 100.5 sq in.
Now, the new SVS bass drivers probably have more excursion than the 90s 12", so the SVS towers will win in the bass department.
So yes, the SVS towers probably are better than the Fortes, but I would have to compare them side by side to be sure.
Compared to a tower like KEF's R11, I would give the win to the Fortes 9/10 times. The KEFs just don't sound alive like a good horn system.
Compared to a Klipsch tower like the RP-8000F 2, I would have to hear both in the same room. The RP-8000F 2 will be much better designed, and with modern driver technology, it has much more potential than the Fortes, but given that the Fortes have a horn loaded midrange, I can't be sure as to which I would prefer.
So given my personal tastes in audio, I'd probably hook up the Fortes in my living room, to a nice amp (maybe a tube amp? They are high sensitivity...), and when I have friends over / when I am relaxing I would turn it up. They aren't a modern reference speaker, but they are special in my book.