This is the area where I really wanted to "big" up the movie. I really wanted to make the space battle big and exciting.
Let me again plug for the Victory. Like several EU items used by West End Games, it was created from rejected concept art, in this case concept art for Imperial Star Destroyer:
I don't know who the artist is, but this art precedes the films, and I think that justifies its presence. See the Wookieepedia article and read Behind the Scenes.
The ships I suggest most strongly are this and the Y-wing. The designers of the Clone Wars series tried hard to stick to a similar design to the original Y-wing, which is of course real OT. It's a variant, and an interesting one to me.
Interdictors are an afterthought, and I certainly don't mind not including them at all. I don't even mind not using the Y-wing, though I do like it.
As far as being conservative, what I mean is practical and realistic. Creating ships is easier than creating characters flying out of Sarlaac's mouth. Also, when talking conservative, I'm talking about being fairly true to the original story. That doesn't mean I'm not open to changes to it, but that the original story was quite enjoyable for me personally (though I know many didn't like it). Completely rewriting the movie is unrealistic to me, and it's an unnecessary undertaking considering the value of the original IMO. Adding ships makes very little difference to the original story. Moving Dagobah to earlier and saying Luke's been training a while is bigger, but it's still acceptable. Making Endor a moon of Coruscant (while not an idea I like) is a reasonable change. But some discussions to me are just too unrealistic for our artists, our budget, etc.
As a final thought, I also don't like the overuse of CGI, but it does have its place. Like I said, it's easier to create ships than people. But who even says it has to be CGI? If you look at my first post, I mentioned model building. I wouldn't mind constructing a Victory star destroyer model, filming it, and compositing it into shots.
Let me show a visual comparison between the two:
They're not too dissimilar. But the Victory is only a little over half the size of the Imperial.