Hi,
Suggest you get the plans book from Nell Hovercraft, it is basically the same craft. These craft have been made by many different companies over the years, and commercially copied in Eastern Europe and further modified. The fact ASV is not responding atm is more indicative of the hovercraft scene in Australia than of the design itself. Built to the plans in light ply it accommodates 45-50hp air cooled, can be proportionally enlarged to take heavier engines and loads. There are also examples with front lift engines running around.

Nell / Viper have brilliant support as evidenced in this build log

http://www.speedjunky.net/html/viper_build_page_1.htm

yamah