I'm not sure of the HP difference, but it shouldn't make enough of a difference just to swap. I would leave the 2.5L in there and turbo that motor. The 2.5 cylinder walls are also thicker than the 3.0L. As you can imagine that there's .5L worth more of metal in the 2.5L. Steve Hernandez (Exile, in the good days) has also stated that previously.
Also, the 6gxx motors are Mitsu

 

....when I say "it shouldn't make enough of a difference"...I mean that 40hp isn't a lot when a turbo can be used to compensate for it after the internals have been replaced with forged internals
By no means do I mean that 40 hp is nothing, lol.

 

so if I did do the engine swap and turboed it, It would be approx 40hp more then the stock v6? But the stock engine should hold up better and last a bit longer??

 

The 3.0 swap will dyno around 200 hp at the wheels ...I thought the 2.5 was around 160hp at the wheels so you are +40 as it sits no turbo ...