When you said Beetle I assumed 911.
They are after all one and the same. 
Except the above will have the asthmatic and troublesome type 1 air cooled hitler special where as a 911 has the far improved van engine that is the type 4
I ran a '59 1172cc Beetle for 15 years and only had to replace 2 exhaust valves, and drove the car flat to the floor whenever possible. In my experience they were a superb engine. 
I have rebuilt a few now and each one had shot mains and overheating issues.
That said they were 1.5's and 1 off 1.3 so slightly more stressed than the 29bhp from the 1.1.
The harsh reality is that they rely on the oil for the serious business of cooling the valves and the pistons etc and the type 1 oil setup is horrific (much better on the type 4) with there not even being an oil filter as standard!
There are a number of ways of improving things with a bit of work but, hard fact is that if you want more go, get rid of the type 1
