Glad to see another Helms 25 getting re-fitted. David (last poster in the bimini thread) also has a 1975 and has done alot of work on the boat. Also Kevin just got an older Helms 25 (I think a 1973) back in the water this year.
Sailnet use to have an email message board that a lot of Helms owners used. The archive is still available. Look under resourses, email list archives and then under Helms. There is a lot of good information from those folks.
Tell us more about the history of your Helms and what you plan to do to it. We are always finding out new things about how these boats were made.
You may find some of these items handy.
Older Helms spec. Notice the older Helms insignia on the sail.