The firmware for HWID 0827 models is the same whether the model is 250W with HWID 0827 as yours is, or any 2x5W [i.e. 205W/255W/265W] with HWID 0827. As my rgn in the original kit was made with 2x5W fw, and is identical with your rgn made with 250W 0827 that's conclusive evidence. If the hwid is the same so is the fw.

As the simple conversion with original boot bin doesn't work, i would be inclined to not do a full conversion using the complete 465 fw as you may irretrievably brick it. It may work to compress the 465 fw_all.bin and retain the hwid, but frankly i think you may be better to just be satisfied with your progress this far and not push your luck any further. Perhaps the SW guys might give some further advice and opinion, but i feel there might be some subtle differences between the 205W 0827 and the 2x5W 0827.