The 24v head won'T fit on a OBD I or II VR6 block...it's completely backwards, plus the timming chain is on the opposite side...
as for S/C, there are really 2 main ones for a VR...
1.Z-Engineering: cheaper of the 2, easy to install, relatively good power enhancer. Although, I've heard of belt "slipedge" alot..but anyway..If it breaks on you, cut the drive belt, and just drive home..
2.Vortech: if you have the money, get this one. It's a bit more complex to install since you have to run oil lines, and I think you need a more powerful fuel pump. Good power, and posibility of a BOV!! what a sound... This is a more reliable and more powerful charger..
I've seen a 3L VR6 on the 1/4, nothing spectacular...
That's why I want to run a 100 Dry shot of NO2!
-Eric