Right, done some more digging (hopefully not deeper into a hole) and would appreciate some confirmation.
The 7GB iso of my xbox1 disc created with xbc can be burnt to a dual layer disc in the usual manner and used in my xbox360 as it's a backwards compatible game. No worries.
If I want to create a single layer copy for use in a modded xbox1 console, I have to use an app like xdvdmulleter. I understand this now.
New issue:
Following soso's guide, using the create iso in dvd5 format, I make a 4.37GB file. With no xbox live, do I have to worry about stealth and ss, dmi etc? Can I just burn the mulleted iso to disc and play?
When I've ran the iso through the checks it noted 'video appears perculiar' and some tick boxes were left unchecked. Work or no work?
Then I thought instead of remaking the iso from the xbc extraction, could I rebuild it by using the original disk in my SH-D162D.
Clicking the option load from dvd, the game is recognised and I select create standard xbox disc and it makes the iso. It takes longer than the other method, but the files are the same size. When I open them for inspection in mulleter both versions have the same folders and files etc... I've browsed the contents of each iso, though the tick boxes are different.
Will this ripped iso work?
Ta