The las + ccw is the best combo for this. With a ML/autocannon I can't fire most of the time anyway as half of the dread is going to be covered by the LR - and the ccw is there to protect the castle from incoming troops. If I had points leftover I'd take lascannons on both dreads, but the second dread is getting a plasma cannon instead.
This sucker needs to be painted by Saturday!
This army list I'll be using will be Blood Angels in name only. LR + dread castle, 10 terminators, nothing about that is traditional BA. Will it work? I think it can, I have had success running the same strat with my own GK force.