head casting number 4772576?

BJR,

Unfortunately, I don't have a flow bench. But I couldn't help but wonder if the heads were flowed at 28" or the other # (forgot at the moment). The numbers are comparable between the two heads, which is interesting. But they appear much higher than any other data I've seen at 28" for either of those heads. I've heard of pros and cons on both settings and recall that it would change the final #'s.

Do you have any #'s from the same bench on the older 360 heads as well as 308's with similar prep for reference and comparison to those heads?

I have several virgin sets of bare 576's. But the ones I had machined required milling to bring them down to the 65cc range. OEM tulip-style valves do have a somewhat deep "dish" when compared to aftermarket stainless nail-head valves. But I'm guessing that the difference might be a cc or two. Could the 576 heads in the photo been factory machined assemblies that had been milled?

It's my understanding that the 576 heads are very similar to 308 heads, but without the hole beneath the exhaust ports.