Hi Graham
first, suggest you enter the word “kingfisher” into the junk rig Knowledgebase at http://kb.graymatic.com/index.php
this will list a bunch of articles about kingfisher boats including sail plans and rigging plans, I think.
if you can’t find the sail plans specifically for the 20+, email me: I think I know someone who might have a copy.
But, that’s not the same as a plan for how to do a conversion, and maybe some of the forum readers can help with that. There were quite a few conversion articles in the magazines in the past. Again, just enter the word “conversion” into the Knowledgebase to get those. (There are 1,100 + items indexed in the Knowledgebase at this stage.
Finally, you could always email those members who have Kingfisher 20s if there are specific questions, but always good to start on the forums so we can all share in the info
best