The problem with that is if you look at the weight differnce between the vehicles it.makes more sense to just do a whole engine. All that work and money will get you further with a 3.8.
I agree unless you have exhaust sound as a high priority. The 3.1 will sound much better than the 3.8.
97 GT white 4 door-SOLD
Cherry 2005 Impala LS- Front and Rear GMPP Strut Tower Braces