The Revell 67 Corvette Roadster is a nice little kit. I've built one, and I'm going to build another and tart it up with some PE. AMT makes a 63 Roadster. I think the only coupe I've seen is the Revell 1/8 version of the 65 model. I don't think I've ever seen a 63 split window.
I hear the Accurate Miniatures 65 Penske/Hall Sebring 12 hr GS Coupe is wicked, but it's pricey at $40. That includes PE louvres and a PE detail kit, though.