Can not create a bootable drive / partition on iMac
Why are you installing from  usb?

I recently replaced a hard drive in a 2008 mbp with samsung 850 evo. Using Target Disk mode, connecting mpb to my imac via 1394b/tb, i used the online restore to write the install image to the mbp after using the same connection with DiskUtil to partition journaled mac format.

Despite what the interweb blathering to the contrary claims this works as designed.