Yikes
, I'm sure those speakers sound great with music, but matching a center channel and surrounds to them is going to be a b!@ch. Klipsch used very different materials in their speaker drivers of that era than they do today. The only thing that stayed constant is their Tractrix horn tweeter, which even then they have modified over the years.
I have been through this scenario before myself and I do not know if you really want to take this path. I own a pair of Infinity Kappa 5 speakers from the late 80'S. I decided to search for for a pair of Kappa 8's or 7's to use for left and right and another 5 set on its side as a center because I love the OLD 80'S INFINITY sound. This proved to be time consuming, disappointing, expensive and nearly impossible.
In the end after wasting 4 months of combing the classifieds and e-bay for someone selling a pair close enough to my proximity to pick up, Kappa 7's and up weigh 90 lbs+ each, and in acceptable condition, I settled on my current Mission M series set up for the home theatre and use my Kappa's with a sub for my listening/bed room.
If you want to do this, then call Klipsch's technical department and throw this scenario to them and ask what center channel and surrounds/bookshelf speaker model EVER produced by them would best match these speakers and then search the classifieds and e-bay for the match.
If they tell you some current model, they are just trying to sell you speakers and at that point you should find the earliest vintage speakers available to match.
You definitely have your work cut out for you.