....seem to remember that performance catamarans list old boat parts somewhere and that the rudders for many of the nacras of that era were the same

maybe 5.2, 18sq, 5.5, 5.7 5.8 etc

perhaps with a bit of grinding you can remove whatever material limits your current rudders from coming forward, they don't have to come forward far

ps i also weep for the good old days where we could post pics directly to the forum and not just links to somewhere else where they were posted