... so you want to play semantics?
Let's break this down. First, define speed. You want to define it as pure, top end, absolute peak mechanical and metabolic pace sustained for an arbitrary distance, in this case 200m. Fine. Let's use that.
Here's the first problem with your argument. You have a quantitative data point for one runner, and can only surmise the point for the other. So, you simply cannot state one runner has more speed based on your arbitrarily chosen distance.
Second problem. You're arguing that a runner who could close a 5k in 50 high could not run even a full second faster in a pure 400m race. That seems... unlikely. Using the of Purdy, VO2 Max, Cameron and Riegal performance predictors (yeah, I know they're flawed), a 3:28 1500m converts to a 47.3. Cut that in half and you have 23.65. Probably about a second fast, but it's enough to make my point. Obviously, I'm suffering from the same methodological flaw you are here. I can't use this as a statement of fact. Only probability. And the raw probability based on those quantitative scoring/predictors is that Mo in fact had
more raw speed (by your definition).
Third problem. Does it matter? As you pointed out, there is a difference between raw speed and speed endurance. Raw speed doesn't tell us much here. If we're trying to predict 1500m times, it tells us a little more, though not much. As I just established, based on your arbitrary measure of speed, Mo likely is "faster." This alone renders your whole argument unlikely to be correct. But we're not trying to predict 1500m times. Marc was a 5k/10k guy, where aerobic capacity is far more important than raw speed. And, like you said, elite distance runners aren't really that "fast" compared to sprinters, or NFL wideouts for that matter. But that measure of raw speed doesn't tell us a thing when it comes to predicting mid-long distance performance. Are we really arguing that Tyreek Hill has more potential in the 5k than Marc because he has more raw speed? This renders your argument pointless.
Finally, I appreciate Steve Cram. Great athlete. But appealing to authority doesn't make your argument any stronger.