After almost a year of restoration, both body work and engine, running it in and having it setup last week, I decided to go back to a standard Cam and loose the laggy 285T2 and the fucking head gasket has gone within hours of me fitting the cam!!

I cant understand why this would happen?!
The AFR should not have changed, I marked the Dizzy so that it went back in exactly the same place to maintain the correct ignition timing, i'm only peeking at 17psi and holding at 10psi, and going back to a stock Cam should let less air and fuel mix in making the engine run a little cooler.
Why has the gasket gone??
Is there something i didnt think of?

Karlos.