I did a swap recently of a ucf20 ls400 ecu to celsior.  Video here 
It resulted in the egr being turned off without codes and a code behind for hydraulic fan.  Car ran fine and code didnt result in check light. 
Have you not got a good ECU rebuilder you can use?  I would be happy enough to swap to a celsior ecu however I have the advantage of trying one first as I keep a test ecu from each ecu range.  Cheers.