I have a bit of a leak happening around my head gaskets. Got the engine second hand off a guy who had 'just done the top end' and he has used a gasket seal on it. First track day out it leaked a bit (pink coolant and pink leak) but since then it seems to have stopped leaking a visible amount.

Is it possible that it leaked first time out then somehow sealed itself though prolonged heat of a track day? Bit perplexed really.

How common are these leaks and what are the main dangers?

Also looking to ditch the stock coolant overflow in favour of an HRC style one. I assume that the radiator doesn't really require a backup coolant supply so the bottle is used more as an overflow and breather?