It's an interesting project that would make the boat look more modern so I'm not knocking it.
I had a Taipan 5.7 with the new rig on it that your changing to before my Nacra 5.8, couple of personal concerns I have are the hull shapes between the 5.8 and the square top cats are very different. The 5.8 mast is strong but not really a wing mast, is it strong enough to hold the big square top leach up? I had a cat before that the mast used to hook over at the top laying off the leach unless the mast was aligned with the main sheet direction. Personally I think the 5.8 was built for raw power that just shoves through waves while most of the square top cats are designed to harness the wind more efficiently and use it more elegantly and I think that starts with the hull shape.