[Bug-ddrescue] How to restore just a single partition of a multi-partition image file?

[Shahrukh Merchant]

I have a ddrescue-generated "fulldrive.img" file of a complete 1 TB 
drive comprising 4 partitions - C: (200 GB Win7 OS) G:(800 GB Data) (and 
2 other recovery/OEM partitions that are not important for this discussion).

I have a current system with a new 2 TB drive installed with the same 4 
partitions, except that C: and G: are slightly larger (250 GB and 1000 
GB respectively) and there is some unallocated space.

The C: partition is the OS System partition and is corrupt (though 
bootable, if barely--various system files are missing). I would like to 
restore just that C: partition from the fulldrive.img backup without 
touching the G: partition on the new 2TB drive.

I cannot see a straightforward way to do this in ddrescue--can someone 
help? Even if I manage to mount just the C: partition within the 
fulldrive.img file somehow (using mount with an offset, I believe, 
though I have never done this), and then use ddrescue to "clone" that 
mounted partition to the desired C: partition on the 2 TB drive, I'm 
skeptical (or at least wary) that that will result in a bootable system 
partition on the new drive.

I know I can also do it with a 3-stage process:
        ddrescue from fulldrive.img to a "spare" 1 TB drive
        ddrescue just from the resulting C: partition to cpartition.img
        ddrescue from cpartition.img to just the C: partition of the 2 TB drive
but that seems rather a brute force and time consuming approach and it 
seems that there must be a simpler way!

As a clarification, all drives in questions are completely good (at a 
hardware and partition level), as is the ddrescue fulldrive.img file. I 
am using ddrescue strictly as a cloning/backup/restore resource in this 
case, not for recovery from a failing drive.

Any solution that I'm not seeing? A Google search didn't turn up 
anything clear either.

Thanks,

Shahrukh