Asking for plans may well be going about this the hard way-- it sorta implies that you are looking to scratchbuild all the lost/broken parts.
My first thought is that this may well be more work, and take longer than just starting over with a new kit. (But maybe the fun of the challenge is what you're after.) These kits have been in essentiually cointinuous production for over 40 years, so it isn't like you're restoring an un-replaceable antique.
If you are set on restoring the original model, I suggest looking for partially built kits. I've seen a lot of kits that were started by people, who built the hulls, but never moved on to do the masts and rigging, as they had either lost interest or were overwhelmed by the complexity. I've seen partially built kits for sale on Ebay for a fraction of the cost of a new kit-- sometimes the original hull has been lost, and all the seller has is a box of masts, sails, and other rigging and detail parts, which might be perfect for you. In general, incomplete kits sell for pennies on the dollar, and they'd make perfect parts sources for a project such as this.
Hope this helps...