May not be but with a phone call to the Chevy Dealer he'd know for sure, I know it will work for the newer LSA motor which is the Cadillac supercharged 6.2, which is what is going in my project.
In my case I didn't want to go thru the process of guessing what was what and eliminate the VATs and other programs that my old 67 doesn't have. In my research it was very easy to reflash the ECM if you had the correct Tech II (not sure on the proper name) reprogrammer etc..... and for a fee there were alot of folks that would do it.......... however sometimes you didn't get the reflash for your exact application, you get one, that would work but it was for whatever vehicle they had purchased a license for ie..... C6 vette, which would probably work on most LS based motors etc..... but not the SC LSA etc.......
So I opted to fore-go the donner ECM in favor of a GM Performance plug in play ECM that was engine only and not all the other stuff I didn't want or need. May not be for everybody but IMO it is a sound option.
At the end of the day....... His vehicle, his money, and his skill level