Internal dimensions of aluminium / unibody / retina models?

Hello,

Where could I find the internal dimensions of the aluminium, unibody and Retina iMacs?

I have a project in mind where I would like to use the iMac as a case with display and replace the internal components with a modern laptop motherboard, giving me USB 3.0, NVMe storage and less power consumption all while being nice to look at.

So as an integral part of project preparation I would like to know which model would give me space problems and which one is the most viable for such a conversion.

CAD files would be a godsend, naturally.

Thanks for any pointers!