SOPMonkey:
Ok I stand corrected on that.
On first generation aircraft of the sought, we weren't hamstrung by the N1 restriction.
I have worked on all Boeing jets since 707 with the exception of the 777 and the 787 and am licenced on the 737NG, 747-400, 747-8, 757 and 767 plus the the MD11.
All of these Boeings have a similar mechanical interlock, which prevents the reverse levers to be pulled up unless the thrust levers are in idle (and similarly prevents the thrust levers to be pushed forward unless the reverse levers are down). Another solenoid activated interlock prevents the reverser levers to be pulled above the reverse idle stop if the reversers are not fully deployed.
So you have to pull the thrust levers into idle before you can pull the reverse levers up. Additional interlocks prevent you from depoloying the reversers in the air.