And just remember, If you mill the heads and need to mill the intake to get it to fit, those parts should always be used together on the next engine (if there is one).. I milled the heads on my 273 and already had them bolted on when my intake didn't fit. I machined the intake instead of unbolting the heads and machining the intake surface. No worries though, the heads were 2 different numbers, I had them ported, and the intake was a CAP intake not correct for the car. I have since picked up a nice set of correct heads and intake if I need to change.
