I am quite new to 10Rs, so am no authority, but to quote from a Yachts and Yachting article "Any boat can be a 10 rater and several Marbleheads have been successful in the class by conversion with just one larger rig giving 40% extra sail area" so this could offer another avenue to explore. Although not necessarily hard chine, there are lines available for a number of Marbleheads, including Brad Gibson's Indie.
Also PJ Sails offer the hull for their Tension design 10 rater for a not unreasonable £175.
Have a chat with Roy Stevens (roy 'at' grtayton.co.uk), I've currently got his 10r Sonix round the back of my dining table and I know he is looking to sell her - I sailed her in this years nationals the other month and thoroughly enjoyed myself, even won a race which is a miracle for me. Plus the price is very good.
I would like to spend the winter months building what I hope will be a reasonably competitive boat. Not having sailed/raced this type of boat I could really use some help from those in the know advising me where to look for 'race winning' plans (ever hopeful) and indeed which plans to avoid !
Any thoughts / help / advice would be much appreciated. Regards and thanks for reading … Chris