The pain comes with the apparent scale of the Revell kit. The little ISTs you can see here really are tiny in comparison to a WH40k figure. So the cockpit of the republic gunship, which takes a whole seated crew clone and his oppo; and their ejector seats, are most likely going to be replaced with the top portion of a cadian torso and a head. If you can imagine a real person in a glider, that's what it'll look like. fortunately, with the canopy as well (not as clear as the valk one), it should be ok.
The gunship was from www.modelhobbies.co.uk for £22.98. With suitble changes to the weapons and perhaps a mod to turn the pointy pods on the roof into engines, it certainly has potential.