It has been done before, but it is not a popular swap. There are a few technical merits to the V6 over the more popular V8 swaps though, namely weight distribution. The engine is mostly behind the front axle centerline with the V6, and the V6 is lighter than the lightest factory V8, thus giving vastly improved weight distribution. I researched the swap years ago for my car, but the cheapness of an SBC won out due to my limited income.