Just to add on the head comparison; depending on fuel octane and dynamic compression, the AL heads are less likely to experience detonation.
I would much rather have heads that allow for more tuneability in both timing and cam selection.

@jman; are you running flat top pistons and has the block been decked? Also, is it auto or manual? If auto, what is the TC stall? What is the diff ratio? There are several factors to consider before selecting a cam..

In my case, I had to change out the original #62 heads for a set of 6X-4's because of the low octane fuel here in California. I was detonating all over the place. If I had the $ I would've gone with AL heads. BTW, It's no fun to R&R iron heads with the engine in the car.