The side stabilisers would work, but if anything, if we were getting into physics, which is nothing to do with Freespace, the effects are even more difficult to control in space because there is massively reduced friction or pressure to stop the ship rolling when missiles are fired

Anyway, as I said, I'm not here to talk about physics, and theres nothing wrong with the look of the ship

Looking at the picture, my one concern is that you have a polygon missing on the base 'spike' part of the ship, at the front, and I'm not sure about the polygons around the missile ports either. I hope it is just compression error from the JPG.
I think it's a little small to be a gunship to be honest, I always picture them as small cruisers, more like a Missile Boat certainly, or 'Heavy Escort' might be another good role for this ship.
Flipside

One little thing as well, I think the ship needs 2 'widths' across the top, I must admit though, I have a big dislike of squares, I think it would look better if you made the thruster part of the ship more pronounced and didn't have the missile ports going all the way to the back of the ship?