Well, after receiving a damaged rtx5070 (snapped 12VHPWR plug retention clip) I decided I couldn't consciously stay with a card that uses that awful connector.. Got a Sapphire Pure 9070XT for a similar price new (£600)!
After a few runs in Steel Nomad DX12 I got the rank 1 result for my setup, I believe in Adrenaline I was using:
\+20 Max freq offset
\-130 Voltage offset
\2800 VRAM on fast timing
\+10% power limit
Ran at a cool 46c with 72c hotspot under 100% load with around 350w power draw. Won't run it like this in games but crazy to see how well these things overclock! More than happy with it and hope it's useful for others wanting to get the most out of them.