It might be tough to find a good match for those Kappa's- it's been a long time since they've been in production. I'd suggest you might be better off getting new ones.
BUT, those are some damned nice speakers, slevestain. What kind of shape are they in? Are the surrounds still good? Are the tweets original? You might consider keeping them around for a 2nd, stereo-only system, if that's practical in your situation. After all, if you need a new reciever anyway, why not move the whole thing? You can get better overall performance for HT by buying a matching set designed for that purpose. But those Infinity's are still elite music speakers, IMO, and would compare very favorably to anything you're likely to find for under $1500 or so.
Lastly, if theyr'e in good shape those Kappa 7's can bring a good price on Ebay or sites frequented by vintage gear fans. If you decide to sell them, drop by
Audio Karma. You'll find mostly guys into the older but still great vintage gear there. (Hmmm...the link doesn't seem to be working right now- it's >audiokarma.org<).