Try to find a complete unit (harness, PCM, transmission of your choice, etc.) There are plenty of them out there so I think it's better and cheaper in the long run to find one the way you want it to start. I would try to find an F-body engine from a 95 or later so that you have the right accessories, ODBII, and a vented opti. I have a 94 and updated to a vented opti, so I know how expensive it can be!
Here's a link that talks about the vented opti, ODBII, etc.
http://forums.hybridz.org/showthread.php?t=90482