I am on the look out for any plans on machining your own engine, would like to build a horizontal twin, but anything would be a good start, used to remember plans available years ago, but it was probably a diesel.

Anyone come across any ?

Here's a couple of links. Might not be what you are looking for, but follow the various links on the pages and see what you can find:

http://www.engine-museum.com/

http://www.bobshores.com/pages/1/index.htm

Good luck,
AV8TOR