since your board has only 3+3 power phases my hypothesis would be that you won't get past 3.8ghz. Full atx boards generally have more power phases.
Since you have the fewer phases rather than more I would go with the bigger heatsink to run cooler. Like the noctua nh u9s. Since you're on mATX I guess the bigger nh-d14 or 15 won't fit your chassis.
The more power phases you have the more the load is distributed between them so the vrms don't heat up as much. What's the odds there's a decent heatsink on the vrms? Not very high. It looks quite small compared to the TUF vrm heatsink on my sabretooth.
You're build isn't well suited to overclocking. That's why you need to be careful.
I already said go 0.1ghz at a time and monitor the temps, at each stage but I think it's going to give you a hard time without a stronger cooler.
I would have bought a full atx board with more power phases and a larger vrm heatsink too. Granted that you're on a lower tdp platform than mine what is relevant is overclocking puts out more heat than spec. and the manufacturer does not recommend overclocking so the heat sinks are only primed to offer good performance at standard voltages.
There isn't an easy way to add more metal to the vrm heatsinks but you should find an additional fan to huff on the vrm heatsink too. and 3.8ghz is probably too optimistic.
What I might do in that situation is get the noctua and stick the wraith cooler to the vrm heatsink with thermal epoxy if there was room for it. There would be on a full atx board. That would probably eliminate any worries but then, without knowing exactly how much heat each component will take, the quality of the vrms, and so on, it's a certain amount of estimation not any guarantee that all will be fine.
It might be somewhat better if you jury rig a larger heatsink to the vrm heatsink as well as utilize a larger cooler.