I dislike the plasma tactical squad. Make it another melta squad. Plasma is too risky and not so needed at the moment, melta is though.
Then I like
LCs with Khan

Seriously that is a lovely deathstar, coming in from the side, enemy will not know which side to avoid. I would add some
SS/
TH just so you can down tanks or harder enemies or whatever the enemy has decided leave by the side[20'' from the side charge range?]
Dreads as you were saying do not fit. Try typhoons which can hide better or deepstrike if your units decide to outflank. I think you need to be brave and in the enemies face so dreads sitting back will not be for the best, so more attack bikes could be fun.
Maybe razorbacks with 5 marines could be good, they have longrange and can out flank. Also with twin linked flamer they sound fun.
Also dedicated transports also gain outflank so you deploy the troops in other manners if need be.
Good luck