Jim Greys will run 450bhp flat out and starting to lean off quite badly at the top end, the most they usually get ran at though is 430-440bhp like you say. Theres no chance it would have made that power on a T34, would have been more like 390bhp Max imo.

Allways makes me laugh when you get people saying i have a 440bhp from a T34, Funny how they get made to look stupid by a 420bhp T4 powered car isnt it?