This thread has many useful references (recommended books, DVDs, blog, etc):I know that this is off-topic, but would you be able to share a list of the books and DVD's about aircraft VW engines that you mentioned?
Steps to scratch build a VW
Posts 4, 11, 22, 28,, 37, and 40 seem most responsive to your request.
There's a lot of info out there. Some of the info on VWs for performance cars/racers is interesting, but aircraft use requires high reliability and good output at moderate RPMs (3400-3600 and below). That's different enough from street racing that it's a good idea to pay closest attention to sources (including people) that are focused on flying Type 1 VWs.