Mount your completed Windows install .vhd with diskmgmt.msc

Run this in command prompt, replace %drive% with the mounted .vhd root Windows partition drive letter (not the 500MB partition)

dism /capture-image /imagefile:C:\install.wim /capturedir:%drive%:\ /name:"install" /description:"install" /compress:maximum /checkintegrity /verify /bootable

Replace the install.wim on the stock ISO with the newly created install.wim