Is building a stroked 318 better than a stroked 340/360?

I don’t understand the mind set of building a small bore block. Bigger the bore means less shrouding of the valves and equates to better air flow. Air flow makes power. Which if you’re building a stoker you’re after power. Also a little math helps justify it as well. If the engine is expected to make 1.x hp per cube do the match on the cubes as well.