Yup using the std Y-table-10.stl
Actually I am currently using 4* 215mm pcbs as my bed heaters so hole-hole pitch is 430mm hole to hole. Outside dimension is whatever is needed on top of that.
(Although my next iteration might be a silicon bed stuck to the bottom of the build plate, so I can reduce weight.)
I'm at work and can't measure, but I kept the build plate edge the same distance from the y-table as a stock 200*300mm (essentially just extending the length of the 'frog legs'!).