The Nacra 5.2 was last listed at 79 by Yachting Victoria in the 05/06 season. Even then it was only in the archived list as no results had been received since 2003. 5.2's haven't been raced in any numbers for about 15 years in Australia. However I think a good one well sailed with crisp sails should be able to compete at 79. The link to the old numbers is here.
http://www.vic.yachting.org.au/site/yachting/vic/downloads/Yardsticks05_06.pdf

Cheers
John Dowling
Geltek Flyer 11 AUS917
Stingray 589
Seawind 24 179
Arrow (????)
MG 14 1712
(When too many boats are never enough)