As I recall it, Boeing procedure was to fly level waiting to reach gear limit speed, then select gear down and descend at gear limit speed with full speed brakes. This was on B707 and B747 classic for many years.
The big down side here is what if there is some airframe damage and you lose hydraulics during the descent? The Pacific is a big ocean and you're screwed if you cannot raise the gear when you level off.
The times to F140 are close to the same with gear down/gear limit speed or gear up/Vmo as I recall it. The thing which persuades me that gear up/Vmo is a better option is that you start to lose altitude almost at once rather than wait for the speed to wash off. This means that you are getting your pax into a more benign environment quicker.