The Ageless radial engine plan packages represent over 70 years of development and experience by Sam and Lee Hodgson. As should be expected with such a mature product, they are more than just drawings. The set comprises, drawings, job sheets, jigs, tooling, etc, etc. For a review, see the Model Engine News review link below. If any testimony to their quality is required, just look at the number of running examples of these engines that exist. Even if you are not going to build one, reading the job sheets will provide a wealth of ideas for other projects, both simple and complex.