I don't remember the brand, but a friend of mine installed an aftermarket sliding ragtop in his 63. It had two options on the installation, one was easy and one was correct. He probably spent 100 hours on it doing it the correct way, but if you didn't really know ragtops, you would think it was factory.
A company called Street Beat makes (or did make) ragtop kits that are/were supposed to be easy to install . . . mark a line around their template, cut a hole in your roof and bolt it in . . . but I've heard lots of bad things about them (leaks, noisy, general poor quality, etc.).
You might be able to install (or have someone else install) one cut from an original ragtop car . . . if the roofline is the same on a standard Beetle and a flat window Super Beetle. Original ragtop roof sections show up at swap meets and on eBay from time to time . . . but with the originals, usually if you can afford 'em they aren't usable, and if they are usable, you can't afford 'em. and as you can imagin, it's not an easy task to replace your entire roof.
