The max TDP for this is only 45W. If you clock it down, since CPU power not really an issue, you should be able to get away with just the heatsink and fan off. The motherboard might scream about it so you should boot it with the fan on, change any applicable BIOS settings before unplugging the fan.
As long as you have a heatsink on the cpu, with at least some air ventilation, the CPU should be fine if it settles at some reasonable temperature, core temps up to 70C should be fine. If you're not going to run the fan, removing it from the sink would probably help as well.
If you want to get a bigger heatsink, you should look for one with wider gaps between the fins. Tighter fin spacing are better for forced air cooling.