Convert raw to vmdk
Using qemu-img;
$ sudo apt-get install qemu-tools
$ sudo qemu-img convert -O vmdk rawimage.dd /path/to/output/file.vmdk
750GB raw image (acquired using ddrescue/dcfldd) converted using above method took ~2 hours on mid-spec machine.
Create new virtual machine with required resources
Select existing virtual disk
Select above file
Note: won't boot directly in VirtualBox without changing settings (notes tba)
Using VirtualBox/VBManage
$ VBoxManage convertfromraw imagefile.dd vmdkname.vmdk --format VMDK
750GB raw image converted to 750GB VMDK in 1hr 45 on mid-spec machine.