I put at the end of this post a random bunch of old photos I had saved of Kitfoxes with Zenair or Czech floats installed. I thought if you hadn't already seen them you might like to. As we all know when it comes to building things, sometimes a picture can be worth a thousand words...
(Incidentally, the blue, red, and white Kitfox IV on white Czech amphibs is a short wing Speedster version as I recall...FYI )
In addition, just below this post you should find a mechanical drawing of my Aerocet float details with dimensions. But more importantly it shows my full scale drawing of the fuselage attach brackets you will probably need for installing your floats on your Kitfox. You might still be able to buy those fittings from John or Deb at Kitfox? But if not you can hopefully make your own from the drawings on that sheet. I traced them full scale and then scanned them into digital, so I'm thinking if you print that page on an 8 1/2 x 11 piece of paper, you should probably end up with a full size template. And if not at least the fuselage attach fitting concept is there for you.
But if you do end up making your own, I would recommend making the fittings longer (per the hashed lines I added). That way if you need to you can adjust your float rigging up or down without having to buy all new (expensive) strut material.
Paul