The 616 is a reasonable receiver, although the sets you're looking at (especially the KEFs) would benefit from something more.
If you can arrange an audition see if the HiFi shop can partner the set with a similar receiver so you get a feel for what they will be like when you get them home - there's nothing worse than being immersed in beautiful sound because the store have demoed your set on a superlative receiver only to be unable to get the same results on what you have at home.
Beat of luck, do let us know how you get on!