Sail design and boat balance

The Formosa 42 Ketch is a William Garden design. I own one built in Taiwan in 1977 and have tried to restore her to the original configuration. I am having trouble heading up in moderate winds in order to reef. Also I am considering the purchase of new storm sails and need to determine the size of a spitfire jib and try sail which will give good balance as well as a heavy weather jib which will balance a double reefed main sail.
Can someone provide advise or a source of information for making calculations on the forces which would allow me to size these sails properly?

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Gil

I would suggest contacting William Garden. If he can't help, ask him to recommend a sailmaker who can.

When you had trouble coming head-to-wind, did you have your mizzen up? What if, in heavy air, you changed to a storm jib early, then reefed the main while keeping the mizzen up?