Hi Dom,
I am looking for a very similar Z plate to be made if you are interested in providing the Alu and making it for me ? (at my cost obviously)
I have ordered a Chinese "80mm spindle" mount to go on it ;
Top quality mount bracket Clamp 80mm diameter for spindle motor free shipping | eBay

I will give you the exact dimensions when you confirm. Needs to be sent to N.France..