with these heatsinks and at least a fan blowing on them or a cover to direct the flow of the stock fan, you could try 43k resistor too.
Higher than 43k, and it will stop sending shares after a few minutes or seconds on mine, even after extra cooling.

Thanks for your feedback on ferrite beads removal and direct soldering for less heat

Btw, where did you get the heatsinks from?
the bigger ones look like they were made for CPU.
The small blue ones are nice and I like blue.