Refuting blackbird folklore

There was a time when I thought that
the blackbird could secretly hit 5 on the
mach meter--but isn't there solid science
agains this? Such as:

I don't think the engines have the ability
to rev up to such a speed. Maybe the jet fuel
itself cannot produce sufficent BTU's (thrust)
to propel it that fast, maybe the fuel lines
are too small to exceed Mach 3.3

Perhaps the real inhibitor is the lack of
enough combustible oxygen to feed the engines
to shatter established speed records.

I know that the outer metal shell of the
jet couldn't sustain the high atmospheric
friction.

Am I right about all this, or is there OTHER
things to consider?