I'm not sure that there is a definitive "correct" sail size. When I started the site I was a little coy about putting measurements on the site as Chris Jeckells had suggested, when I visited to go through their archives, that there was a certain amount of trade secret about some aspects of the measurements. I am more relaxed about that constraint now, but you still won't find definitive figures on the site, mainly because I no longer believe that there are any.
For example, early boats (those with black spars and those immediately afterwards) appear to have had a different mast that later Reedcraft boats, which didn't allow any adjustment in boom height. Later masts do.
If you look at the
Sails page you should get a good idea of "acceptable" dimensions - although they may be a little hard to read from the images of the various sail plans. If you need specifics I'll check the originals and post them here.
Like Ian, I suspect Enterprise sails aren't a long way adrift, while
Phil Brown, on his boating site, reports a main sail from an Osprey dinghy "fit perfectly".