This excellent book, by L M (Bill) Williams, covers the technical elements of designing and building an Austin Seven special-  many examples are given, with all aspects being covered, including chassis layout,  engine tuning, and so on.

This is also an invaluable reference for the Austin Seven owner- very detailed specifications are included for various models, as well as much technical information.

Will also serve as an inspiration for the special builder, and for the restorer.