Hey, the old IWG2 delta that I got from Min Wu! To be honest, I tried it myself, but all the chinese text got in the way of item descriptions and journal entries.
I've heard others say they didn't care about it, and kept playing the delta. It has completed the Throne of Bhaal portion, which the beta only has a few maps from. Still, I prefer the old beta over the delta myself.
This is my latest version of IWD2_4dummies, if you want to try out BG2 in IWD2 engine.
Here's a comprehensive link-list of all IWD2 mods, which run with IWG2.
To answer your question: IWD2 is coded very differently from BG2, so it's not quite so east to import the whole adventure into that engine. You definitely can't use any BG2 mods in IWG2, because the IWG2 conversion is very specific. It will ONLY convert BG2 if it's exactly as specified (basic install + baldurdash). And since the game is then played from the IWD2 folder, installing any BG2 mods afterwards would change nothing.