There has been a lot of talk around, about adding a Turbo to a Naturally Aspirated engine. I was once interested in performing this transformation, however since reading a few comments around the internet, I have mixed thoughts on the matter, and I don't believe it is worthwhile.
There are many different comments from people why its not a good idea, some of which relate to different head design, to different pistons and rings.
Just yesterday I found some information, stating not to use an SD33 head gasket on an SD33T engine, as it will (can) block water galleries and oil holes.