Failed to install 10.2.7 on a new Dual 2.5 GHz

Using target disk mode I was able to install it from my elder G5. But the booting doesn't work. I see a stop sign immediately in Open Firmware.

This seems to not be easily fixable.

Target Disk Mode is very slow. Copying files over Firewire is about as fast as copying a over 100 MBit/s network. I would hazard a guess, that using a 1 GBit/s network would be much faster. Fairly disappointing.