You can drive it as hard as you wish. It won't blow a head gasket due to your driving habits and it won't spin a bearing either.

Head gaskets wear out with time.........not much you can do about it.

You will cause a bit more ring and groove wear with the heavier combustion loads.........how much more is uncertain.

The engine is very heavy compared to it's power output..........there's a lot of margin there for almost unlimited high power operation.

Personally, I think you can drive it as hard as you wish, but, that doesn't mean you can rev it to 4400 on an unlimited basis. If you keep the rpm's down below 3500, it will likely last until a chain or a guide lets go. Very few people actually wear these engines completely out.........usually a peripheral takes them out when they get old.