The unshrouding has a minimal but significant effect on flow. 95% of the flow occurs against the wall toward the plug in the open side. You can see this by the washing that occurs at that point. Because the heads have very low intake ports and a sharp short turn, very little actually happens on the short side of the intake other than turbulence.
The amount of unshrouding that is done on that chamber is similar to how a performance head is ported anyway, so basically it's just a step in the right direction, but nothing that a properly massaged SC head doesn't already accomplish. The only thing we don't normally do is remove the heart shape because the heart is beneficial regardless. I don't know why Ford took out the heart shape for the police head. Any performance head is going to have a heart shape because it promotes swirl and it helps reduce reversion.
If I was going to make a wild guess, I'd think that the police heads might be an earlier design? Out of curiosity, what is the casting #?
A cam making torque is all about event timing and has little to do with lift except that more lift at the same timing means more flow and more torque, all other things being equal. Fred stuck with the .520 number just because he surmised that most people wouldn't want to go to a bigger valve. I don't question Fred's knowledge, but I think his emphasis on the stock valves was misplaced. A set of SS valves that maximize the available seat area cost like $120, and for barely more than the price of a set of 96803's you can get some 99893's.
I've taken the best stock valve ported heads I was able to get and compared them to a set of totally stock heads that had the bigger valves with a few minutes of attention to the bowls and short turns and a port match at the intake manifold they flowed within ~5%. But when you compare the fact that the aftermarket valves offer you the ability to go to .600" lift, then they actually perform better than the fully ported, stock valve heads at .520" lift.
All without what I would call "porting".
To give you an idea on lobe design and lift vs. duration, for example an old CMRE SI cam was 210/220 .491/.491" lift. Fred pushed the lift to the max on the stock valves with his .520 cams, but the thing is you could order a .520" lift cam with duration anywhere from 206 all the way to 240 duration. Hence the confusion about people running ".520 cams" and getting all sorts of different results. Generally speaking if you want something with 100% drivability you are going to want to stay in the 206-220 range, 224-240 starts to cost bottom end and starts to really be a hiperf cam, at least in typical SC terms.
That being said, if you can go high lift and keep the duration you like, then there is no reason not to do it. Just make sure you have clearance and the right valve springs! I run .580" lift on the cam in my wife's grocery getter. It gets 24mpg if driven easy and idles dead smooth with 18" of vacuum. To get specs any more specific than that you'd have to buy one.
Seriously though, everyone knows how much I like to discuss cam stuff on the boards so don't take it personal, but I'm not going to go into any more detail on cam profiles than that.
Chris, I didn't mean to seem like I was dissing on your comments. Everything I've learned about the SC heads is pretty much backed up on a flow bench though so while I don't have the last word, I do have some inside info as to what the heads need more than anything. All the sharp edges in the exhaust port really bother people but the truth is they don't really cause too much of a problem. I actually think Ford may have done some of that on purpose because they new that the exhaust was going to build pressure on these motors and they wanted to prevent reversion. If you flow a stock exhaust port both directions you'll find that the flow much worse backwards than forward. If you blend and smooth all that stuff away without addressing the real bottleneck (valve size first, short turn second) then what you end up doing is dramatically improving the reverse flow characteristics of the port without significantly improving the forward flow.
There is a lot more to it than that, but you start to get the idea. Common sense and logic don't always prevail.