...I went to great lengths to get my butt correspondingly low...
Paul, despite what Stan says, there's no need for corrective surgery to fit into a Speedster, but the only way to tell how you fit is to sit in one...or two...or three.
The thin, bucket-shaped 'Speedster' seats (copies of the ones in the original Speedsters) are actually a lot more comfortable than they look and put you about an inch or two lower in the car.
I'm 66 and 5'10", and once in the car am very comfortable (there's a lot of shoulder room), but I have to do a kind of dance move to swing my longish legs in.
Once you're in and driving though, you'll be so entertained that you probably won't give a damn about any amount of physical discomfort. The stiff suspension and wind buffeting will beat you up more than a modern car (or even a real VW bug), so you'll probably be wanting to stop and stretch after a hundred miles or so, anyway. Many people liken it to driving a four-wheeled motorcycle.
But what the hell, Ibuprofen's still pretty cheap.