There's not a lot of OCing headroom on Ryzen chips, regardless of the board used - especially while using the stock cooler.
3.8GHz maybe..... and that's if you luck out and don't have to use much additional voltage.
The difference between a basic B350 and a higher end X370 board has been negligible from what I've seen (although the same OC can be achieved, the X370 boards could do it with a little less voltage).