My 440 acted similarly with a tired fuel pump.

I'd go from a standstill to WOT, and by the time I was hitting not much above 60 or 70 mph, it just ran out of fuel, started bogging big time. Let off the gas for a bit so the weak fuel supply could refill enough of the bowls and then hammer the gas again and I could keep going for a little bit. If I was at say 60 and hammered it, the float bowls had enough reserve in them to let me wind it out quite far. But from a dead stop it would consistantly run out of fuel around 70mph. It was, as you say, like clockwork. I made the problem worse by jetting up the secondaries, thinking they were too lean. Of course that just drained the bowls at least as fast as before. I ditched the unknown age fuel pump I had and put in a chrome holley mech pump and now I can peg the speedo w/o problem.