A 195/65R14 should be pretty close to the rolling diameter of the original tyres, so your speedo won't be that far out. A '59 Beetle would have been on 5.6x15" cross-plies. From what I can work out on the internet, they would have been close enough to a 155/80R15. If you put that into an online calculator, as far as I can work out you should have only lost 20mm in overall diameter, which will make your speedo read 3% high.
I used
http://www.willtheyfit.com/index.php
Actually, I just looked up some cross-ply dimensions on Coker Tire's website, and the 5.6x15" is actually a bit taller than that, so your speedo will be about 8% out. Still nothing to lose sleep over.
Personally I run 195/70R14, and I used to run 195/75R14 because I like a bit of sidewall. I just changed down to the 70 series to get a decent tyre with a bit more grip. Not many performance tyres available in 75-series for a 14" rim anymore!
