Alright Darren,
Thanks for your inquiry - you obviously know what you're talking about, whereas i only have a basic knowledge of engines!
The garage has confirmed that the head gasket HAS blown, and there is traces of water in the cylinders - bugger. So i think it is a coolant leak into the head, for wich (correct me if i'm wrong here) the gasket will need to be changed.
Ragrding the smoke and boost, well, the smopke was thick black shite (same as they had today when they tried to run her up), and no boost meant just that - flat response, like the turbo's were'nt even there. Does'nt sound too healthy, does it?
Far as tests the toyota dealer did - i think they did the compression test, and that's all.
Anyway, the garage is whipping the head off today, so i'll give u an update when we know more.
TTFN
Salvatore