Jim, that's the way I interpret it, and the way it's been applied to me personally.
My 1650 motor is the same as yours, 4.000 x 4.000. That comes out to 1647.4cc
At 4.003 bore, we're exactly 1650cc.
I got a 1650cc record certified in '02 with a 4.020 bore (1664cc), taking advantage of the +.020 overbore rule.
I also got a 2000cc record certified in '04 with a 4.030 bore (1672cc), legal as a 2000cc because it was bigger than 1650 + .020
Be aware, though, that there is no such overbore allowance at the Bub meet.