Given the talk of scratch building GT40's and modifying suspension setups, I have come across a good book by Allan Staniforth called "Race and Rally Car Sourcebook : The Guide to Building or Modifying a Competition Car" 4th addition. This gives a very practical approach to designing cars in general and specifically race cars. Given I had to cancel my Ultima project I am now scratch building a bike engined open cockpit Le Mans style car. This book is an invaluable aid. Allan also runs a suspension design/setup service called "Terrapin Services" and he is helping me with my design. Alan is based in the UK (where I originate from) but is willing to work Trans-Atlantic via phone/fax/email. His rates are very reasonable given the expertise and experience he brings to a project.