Out of curiosity, why don't you trust them? To each his own, I'm just curious.
Also since the intention is to make max low end, any consideration for offset grinding the 4" to get longer stroke? That would definitely pump up the torque.
I’m thinking that the 4 inch crank is likely even too much for the head flow I will end up at…plus it would probably just cost less to purchase a 4.25 crank if I was going that route