It looks like you've got all the major parts (excluding the stock, but you already mentioned that being made). You've even got a resin scope, which is cool. If you research the ROTJ rifle a little bit, you'll find some various greeblies (ornamentation pieces, if nothing else) that go on the stock and elsewhere, so make sure you do that.
It looks like advice on filling the cracks has been covered, but I second the JB Weld and Bondo suggestions.
Anyway, hope to see it painted/completed soon. Good luck! 