Minor nit: The Convair 880 and 990 were faster than the 747, I'm pretty sure. I think the 880 could cruise at Mach .87, or higher if they felt like really slurping down the fuel. Those old GE turbojets weren't exactly efficient.
}:-)4
Convair bit off more than they could chew with the 880 and especially the 990. They were the main reason why Boeing built the 720. The 747 can also fly Mach .9 or faster if you're not concerned with range.