First,I don't think standard Chaplains have the option for Termie armor in DA. I think only Interrogator Chaplains have that option.
I don't really like the two Dreads. They're too fragile and easy to take out by the enemy's heavy weapons when there's no other armored vehicles out there to draw fire from them. I would chuck them. With that 250 points,I'd say either another Terminator Squad or a Land Raider. I'd personally go with the Land Raider. It's 14 armor is going to give it better survivability than the Dreads. It's 2xtwin-linked Lascannons will give you some needed long range anti-vehicle punch without having to rely so much on dice luck on the AC's. It'll also let the Termies focus on the opposing troops more. Also,since you have 4 Termie squads,you can Deathwing Assault two on turn 1,transport one up the Land Raider,then either Deep Strike the other as normal or move it up behind the cover of the Land Raider.