Power limits for LA small blocks?

I have a teen stroker, I don't have any idea the hp. But I've been curious to your question as well. I've always wondered why import 4cyl have no problem making huge power with turbos. But small block mopars have some power level were they aren't durable enough to handle? Fella I work with just had his import dynod at over 700hp an runs it at bandimere with all 4 tires spinning. He's still working on that part.