If pricing is a factor, the prices are the exact same between the 331 and the 347 rotating assemblies.
It's just hard for me to swallow topical arguments like this. If anyone has to worry about safety factor, it's a professional engine builder. If a part fails, an engine smokes, etc., it's basically a mark against their pocket book and reputation. With that being said, knowing that my engines put food on my family's table, I would always opt for the 347 over the 331. I would never turn down stroke and displacement for a street engine. A broader torque curve does nothing but help the cause, especially in a smaller engine.
There's nothing wrong with nitpicking, I just like to have a sense of logic behind my viewpoints. That may be the German in you, but it's the Mechanical Engineer in me.
I would consider changing one or more details of your build if you're looking for the power numbers that you're looking for. The 165cc heads combined with a super small camshaft will do a lot for torque, but won't give much in the direction of horsepower.
Of course I'm assuming that you posted all of this asking for help on achieving the goals that you've lined out for yourself. A lot of guys post, asking for help, but argue with everything that is said.