Yes, I believe that if you have the Venture and Dreadnought you can use the Venture parts on it.
Now, when customizing your ship, if you hit 'Advanced', a button somewhere on the bottom of the screen, it should extend your options and you should be able to choose the Venture skin pieces you want to use.
Venture looks better in my opinion, as does the skin (the white as opposed to various shades of gray). Can't use the skin if you mix/match parts (which sucks... hell, I'd still want the ability to paint my ship. Any other game boasting vehicle customization, including the new MWO coming, hail that as a selling point).