Whelp - good news and bad. I didn't wreck the card, and the repaste dropped gpu and HBM temps down by about 15 degrees - while hotspot dropped about 10.
Bad news is the 5w/mk generic blue pads from Amazon performed near *identically* to the yellow pad asus used for the VRMs. I topped out at 108 degrees after about 30 minutes of Furmark. I guess the Minus 8 pads and/or the copper shims are the way to go.
So these are the final temps with decent thermal pads. The hotspot temp still kind of sucks but is within spec, but the VRM has dropped nicely. While I was waiting for my Gelid Extreme thermal pads from Ali Express I bought some Arctic 1.0mm pads from Amazon and stacked them (stacked 3 of them) making sure there were no air bubbles in between. They actually worked quite well, and as you can see there's zero difference between the Arctic 1mm (x3) stacked @ 6.0 Wm/k and the gelid extreme 3mm (x1) @ 12.0 Wm/k:
These temps were captured after 15 minutes of furmark after they'd leveled off, using Arctic MX-4 Paste. I seem to recall my hotspot was a few degrees cooler using Noctua NH-1, so that will probably be my next buy.
Long story short, if you're in a pinch for thermal pads and don't want to spend $$$$ ordering the Thermal Grizzly pads from the UK or EBAY, the Arctic pads stacked will do just fine from Amazon.