Hey Paul,
This depends on how the target system is configured in the BIOS. General best practice for building images is to build them on a Virtual Machine. If you configure the target system in legacy BIOS mode , install windows from the iso, customize it, and capture the image.... you will have an MBR image ready to deploy to other MBR systems. As I have stated before, this image will not work for UEFI systems.
Now, if you have created an image of a system running in UEFI mode, it will only deploy successfully to other systems of similar hardware that are also running in UEFI mode.
The way I handle imaging both BIOS and UEFI systems in my environment, is that I create a legacy BIOS (MBR) Virtual Machine, install windows from the iso, customize, and capture the image. Later if I need to deploy that same MBR image to a UEFI system, I do that with logic scripting. This way I don't have to maintain 2 separate images. Back when I developed this, Ghost version 11.XX did not support UEFI imaging natively. I think its supported natively now....but it depends on how the system is running when you capture the image.
Based on your original post, I am assuming you are not building images on Virtual Machines, so this also makes it a little harder to troubleshoot. For Virtual Machines running in Hyper-V, you can just select Generation 1 which is a legacy BIOS Virtual Machine only. Since you are working on physical systems, you will have to determine if the system can actually run in legacy BIOS mode.
As far as your question about wanting the image to work on MBR, just make sure the system you are trying to image supports legacy BIOS mode. I guess one way you can check that would be to go in the bios, see if you can turn off/disable UEFI mode, turn off/disable SECURE BOOT, and try booting to legacy media such as WinPE 2 / 3 / or 3.1 which is legacy only. If the device boots to these older WinPE enviorments, that means you can install Windows in MBR mode. The reason I don't suggest WinPE 4 / 5 / 5.1 / or 10 is that all the newer WinPEs will boot up whether the system is in BIOS or UEFI mode. This makes it a little more confusing because it will be harder to tell what mode you are actually running in. If you are not comfortable creating different WinPE media, you can just use Windows 7 installation media/iso to determine if the system boots to legacy BIOS mode. If the system boots to Windows 7 installation media, you will be able to install windows in legacy BIOS (MBR) mode.
If you are unable to turn off/disable UEFI mode or Secure Boot in the BIOS/EFI, you could have a system like I mentioned in my previous post that are locked to UEFI mode, Examples of this are again the Surface Pro 3/4, or ElitePad 900s. Obviously there are many other systems like this and you could possibly have one.
Once you have established that the system does in fact boot to Windows/WinPE running in legacy BIOS mode, you can install Windows 10 or whatever Operating System you intend to deploy and the partition structure will be MBR. Then you will be sure that your Safeguard software that requires MBR will work correctly.
Sorry for the long reply, this stuff can get pretty confusing.
If this solves your issue, kindly mark this as a solution. Thanks :)