Hi John, thanks for that.
A good question and one I had considered. I have a 15kg roll of wire in the welder at the moment, so I would have to have a look at how much is left. It would be a very rough estimate as I have used it to weld up rust repair sections and make my sheet metal folder etc., but I don't think it will be a ridiculous amount.
The bonnet alone is 5kg lighter than a steel item and I suspect would more than make up for any additional steel welded in, plus the shell gets a supposed 10% increase in stiffness which is a plus.
The cage will be the killer, so I will just remove weight wherever I can, then compare the weight of the finished product to a standard Mk1. 850kg would be great.