Wait again. Put aluminum heads on it then it will weigh less than a LA. And while you're at it keep in mind the head design produces more torque than the LA head.
I knew I would get kick back on the poly. I have 383's 440's ect. I don't want to be everyone else. I love to walk my own path. A stroked poly that's streetable with a torque storm putting it over 750 hp has super cool written all over it.