kinda sorta help?
Looks like from the pic I linked at the I Heart O'Days
shows you to have a 4-1 main sheet, so tie the sheet at the top of the fiddle on the track, up and thru one sheave of the boom double block, down to the small sheave on the fiddle, up to boom double block, down to the BIG sheave on the fiddle and thru the cam cleat!
You may at some point want to add a 4-1 micro to it, helps in windier conditions. Looks like your sails are similar to my 85 Jeanneau arcadia in size, and that is what I have done.
on edit, HERE
is a pic of a 280 on the hard, but it shows a cabin top traveler, again appears to be 4-1 in nature.