Listing I made in 2004 of various NE payphone specs:
http://www.islandregister.com/phones/ne_payphones.pdf
Centurion Drawings - http://www.islandregister.com/phones/centuriondrawings.pdf
Conversion of an NE QSD-3A for home use - http://www.islandregister.com/phones/qsd3a.html
Conversion of an Ne or WE 233 for home use - http://www.islandregister.com/phones/ne233.html
Converting an NE Centurion for Home Use - http://www.islandregister.com/phones/centurion.html
See Stan Schreier's Controller Design:
http://www.classicrotaryphones.com/forum/index.php?topic=8522.0
3 Slot Payphone Controller - http://oldphoneguy.com/images/WordConv2PDF2.pdf
Another Payphone Controller - http://atcaonline.com/controller.html
Yet another Controller - http://mysite.verizon.net/dalderdi/phones/payphone.htm
If you find any other resources which should be added to this list, pass the info on to me, and I will post it.
Dave