220.55-table-note 1 the value that can be used for your units is
8KW +(5x5%) = 10KW = 41.7A @ 240V
(this is different from the value you came up with but still a 50A circuit)

You are right: 8 + ( 8 x 24%) = 9.92. (I had used 8.4kW instead of
7.2kW, but forgot to update in the post.)

422.31 allows a circuit breaker to be used as the disconnect but only if
in sight of the appliances
These are going to be hard-wired, but the circuit breaker (panel) is
also in the kitchen (right across from the oven and cooktop), so I
assume I'm covered there.

I'll reduce the circuit to 50 amps. (BTW, I already have a #6 cable
there.)

Thanks Bud, thanks Jim.