Ballistus dreadnought for 11th?

Pretty new to the hobby but I've made some second hand pick ups so far. Got 10 intercessors, 10 hellblasters, 6 bladeguard vets, 5 infernus marines, 5 terminator, a terminator captain and a redemptor dreadnought. Would a ballistus dread for 60 he good? I'm also thinking about picking up agatone bc he's good for bladeguard but could some9ne explain why?