have you had a play with
Army Forge?it might make the army building easier, tactical detachments for example are 275 in the latest version of the NetEA codex astartes list
I've been playing marines a lot over the past couple of years, I think you have a decent basis for a list, although you're a bit low on activations as it is... I'd normally aim for a minimum of ten, normally 11 or 12, marines often win by being very hard to finish off and easy to rally, this means you can normally preserve an activation advantage for turn 3/4 and nab objectives
I'd definitely say warhounds fit with marines very well, they bring macro shots to the force which gives you options to deal with problematic stuff by shooting it, they also give you extra activations, they're also fast and fairly durable, and really good for triggering assaults with formations in support fire range, the reaver has its uses but it tends to need babysitting as it's not as tough as a warlord, and can be easily broken by a sneaky assault if you're not careful, it packs a good amount of shooting in, at range, but it also eats up a lot of points in a single activation... personally I prefer the warlord if I'm taking a battle titan as it's that bit tougher