I think the way that GTE's GSi's are set up is that everything compliments each other, where as their camshafts maybe different, they are designed to compliment the ECU's, piston's and various other things. I know that the 2.0 115bhp and 130 bhp models have this problem. It's no good swapping the cam over as there are so many other little bits and pieces that compliment it. You wouldn't wouldn't reap any benefits from fitting the GSi cam.
Not very well explained but I'm sure you understand.