It will run fine with the 3.3 computer. Been there done that. I have done it with 5.2 and 5.9s also and every time it works just fine. When you do swap the computer later on it makes more power but the computer needs to be programed with the VIN and miles on the vehicle or there will be codes for it. The computer can change fuel trim up to 25% before a code comes on for rich or lean and a 3.8 does not use 25% more fuel, according to the EPA there is like 1 mpg different between the two.

Are you just thinking it would be cool to have a few more HP? A gear swap in the 604 tranny is pretty easy too

If you need any assistance give me a PM, I am just at the other end of the lake