Denford Software & Machines

I´d like to fit a 100mm 4 jaw chuck and a collet chuck onto my 270.
Currently I´m working with the standard 80mm 3 jaw chuck but it´s too small.
Problem is that I need a new back plate and the chucks of course.
So far I´ve had a look into it but can´t really work out what sort of spindle nose I have on my machine.
Would anyone know what DIN it follows?

Regards

I´ve done a bit more research.
I can find some 3 and 4 jaw chucks on the internet but due to their exotic size prices are pretty steep
On the other hand I havn´t been able to find a single collet chuck fitting the spindle nose.
Looks like I really have to make a new backplate.

Would anyone now where I can find a drawing that I can follow when designing my new backplate? or does anyone know what standard it follows?
At the moment I can´t really use the machine as the 80mm chuck is just to small. So any help is highly appreciated!