4 seat amphibious plans

We are wanting to build a true 4 seat amphibious airplane. Live load 1200 lbs, 300 Hp range, 150+ cruise speed, composite construction. I have built almost any project imaginable, construction processes, wiring, etc. although I will have questions feel totally comfortable with. The problem is design and engineering. I can not find plans I'm interested in, the seawind is similar but way to heavy and hp needing. I want something along the lone of an Icon 5 but four seat and higher hp and speed. I appreciate any ideas or help.

If you're not wedded to composite construction, check out the Thurston TA-16 Trojan (aka Seafire).
http://www.wanttaja.com/seafire.jpg

Not sure if it's still available, but this site claims know a kit seller:

http://www.all-aero.com/index.php/ho...n-ta-16-trojan

Wikipedia says development is stalled.

Ron Wanttaja

If you are looking for a TA-16 Trojan, I have recently acquired a full set of original blue prints and a completed hull and will be putting it up for sale if you are interested.