Those JVC are a 70s design that went on into the 80s. They are a paper cone tweeter. Nobody uses them anymore(except Bose). They will lack the detail of a "modern" tweeter, but...you can always replace that tweeter with another tweeter...eventually. They won't sound horrible...just won't be as...
We need to know what you have access to, as in brands. Those KLH are at least as "good" as what you had. Matching watts is a pointless endeavor. Within reason...power destroys nothing...distortion/clipping destroys everything.