If you say you have searched and haven't found anything then you haven't searched enough.
This has been done many times, it is a cheap motor to build in the states, so check out the american forums, inparticular
http://forums.hybridz.org/index.php?/forum/32-nissan-l6-forum/
or the starting line document
http://www.xenonz31.com/s130/l28et.html
Plus, best search topic is "l28et"
You will find what you need there.
I also have some parts for sale but postage would be a killer
http://www.viczcar.com/forum/index.php/topic,6592.0.html