Try to get entire engine frame drop out out of a LSS, SSEI or PA Ultra or even the rare 98 Touring Sedan. Then you will have everything you need to go + computor of course. Fastest way to transplant on these cars is complete frame with every thing still all bolted up and hooked up. Exhaust is probably larger for L67, Im not sure but I should know I have both sitting in driveway. If I think of it I'll take a look and my calipers.
Stay away from Grand Prix donor. You will be chasing down odds and ends and be nickled and dimed to death.
There is some issue with the key , pass key, anti theft thingy, what ever that "chip" is thats on our keys. Dont know alot about it except that it has givin some guys a pretty good case.
All L67'* come with the 2.97 final drives.
Or you could just "just" thats funny, put a CSC on your L36. Then you would smoke all of us.
- - - - plus your non HD tranny