I have both engines in my cars and I would recommend the 3800 SC Series II or III engine over the turbo 3.4 push rod engine swap. You will not get anywhere near the desired 300 HP plus range with the turbo 3.4 unless there is a extreme build. With a 3800 SC engine the 300 HP plus range is rather easily achieved with what I believe is a lower cost per HP.
What exactly would you do then? By 'interest' did you mean you would swap a 3400/3500?
I have to admit, I'm biased. I prefer the 60-degree V6 over the 90-degree V6. I guess you can chalk that up to personality quirk.
Plus, when building a boosted 60-degree V6, the 3400 or 3500 is a better starting point than the 2.8 or 3.4. The bottom end is stronger. It has a roller camshaft. And the aluminum heads flow better (and can handle more boost without detonation).
That said, both the 60-degree and 90-degree swaps are going to take a lot of work. The 60-degree will bolt in pretty easy, but will require a lot of tweaking and tuning to get that turbo running right. The 3800SC will take a bunch of work to install, but won't need much tuning. So it's basically six one way, half a dozen the other.
[This message has been edited by Blacktree (edited 10-24-2013).]
I have a 3.4T and it was a lot of work to build. It was my first, so I learned a lot. It requires learning about turbo sizing, tuning, etc etc.
I suspect the 3800SC would be a lot easier from a learning perspective, given a stock ecm will work. No modifications to the base engine are required, etc. I have to believe if you find a complete car it will be cheaper as well.
These guys are speaking the truth. The 3.8 is an easy project.
Turboing the 3.4 on the cheap is like shooting yourself in the foot - it won't last and it probably won't run properly without a lot of fussing about. Doing it right will be expensive. I turboed my 88 GT back in 1991 and I did it so that it would be dead reliable while pumping 10--12 psi. It's been going strong for the last 22 years. But I spent close to $3K on the turbo stuff and another $4K on engine parts and suspension upgrades - special forged pistons, custom camshaft, roller rockers...a long list.
The 'turbo on the cheap' crowd amazes me. They either get poor results or blow the engine up or both.
Do it right and the result is great - about 300 BHP on mine and probably a bit more on a 3.4, but unless you are a purist, go the cheaper way and stick a Buick in.