Thankyou gentlemen for you comments but again it is nothing more than fabrication and there is plenty here that are, and have done great work that would far exceed what I have done.
Grant, you are correct about cooling fins but David did answer what I considered during the fabrication. As I am only using 3mm plate is would be near impossible for me to keep it straight and I didn't think that what I have done would hinder the cooling effect very much and I think that the thinner gauge plate should compensate (I hope)
James

I guess it was a case of have a go or don't use the original engine and seeing that I have made the trans box it didn't seem to much to think about. I will be pretty nervous on the first start up though. That part I will have to video