Key to Fast68s writeup is his comment that to get a "new" set of 906s or 915s to flow like the heads in his test would cost a couple of hundred $ MORE than a set of E-heads.

So, you can spend the $ and get a 40+-year-old head that flows like the E-head, assuming you have a pair of 915s lying around. Or you can spend the money on your set of 906s and end up with good flow numbers but a lousy open combustion chamber. And like happened a couple of years ago to a board member your porter may find a casting flaw and all of a sudden your ported 906s are worthless except for what you have to pay the porter for work already done.

I have a set of 906s in my shop that are worn-out fresh off a 68 383 Road Runner engine and they will sit there until I find a screaming deal on a set of "quench dome" pistons for the long-term stroker. Anything else gets a head with a better combustion chamber.

R.