I have used dd to install the boot partition after recompiling, this works great:
sudo dd if=boot-db410c.img of=/dev/mmcblk0p8
I imagine that you can use dd to copy the partitions to a SDCard, and then use dd to copy from the SD card back to your new system. I haven’t tried it, but I suspect that a variant of this command is a possible solution for you.
Full disclosure, I am an employee of Qualcomm Canada, any opinions I may have expressed in this or any other post may not reflect the opinions of my employer.