Thanks for the answers guys.
The figure of 1,000 seems unlikely considering that was the ships compliment on TNG, and Enterprise D was a lot bigger than Kirk's ship.
One important thing to take into consideration, however, is that the Enterprise
-D was a really big
ship and could likely hold well more than 1,000 people (some estimates have placed a maximum capacity upwards of 15,000 for a short period of time).
The extra space is reserved for passengers/evacuees or for future crew and onboard facility expansion. The same was very likely true of the original Enterprise
, which could probably be reconfigured during a starbase layover to carry 500 additional people in addition to Kirk's crew of 430.