With the change to "Hybrid" small mounts, I think the Hammerhead is almost to the right power level, as that lets you slot in more ballistics to take advantage of your Ammo Feeder. I think, if I was going to make any changes to it, it'd be to tweak up its Ordnance Points. 85, I think, would be about right.
The Venture needs more of a buff, I'd say, to make it stand out in the cruiser range. In this case, I'd increase the size of the cargo hold - 750 would seem to be in the right range, and would make it more of the "mobile base" I think it's intended to be. Bumping its burn speed would be too much of a buff.