OK, I'll make this a place holder for the moment, got to finish the A310/A400 first.
I've been thinking about doing this for quite a while now, got the bits to do it too.
There's not much to go on other than this picture, so some of it will be guesswork. Unless someone has some more info on it, I'll build it like I see it here.
I have read that a water tank size model was tested --- not found any pics of that though ----
The biggest challenge was to find some floats that were in scale with the 1/72 kit (Italeri) but a RC hobby shop came to the rescue there.
I got this catamaran speed boat which has similar hull shape to the floats.