Sure, Sarge
This is the original size from your kit, .4175 or 27/64 inch long (10.6mm),,,,,,,and 23 thou thick. (or around the thickness of a sewing pin)
As for your Gray, that depends on what you are going to use for decals.
16473 is for an overall USAF Gray aircraft, 36440 is for USN/USMC (or Japan for an F-4EJ), and 36622 is for the bottom of USAF in the South East Asia color scheme (35622 is the bottom for Israel's F-4Es)
Do you need some decals for this build, Sarge?
Rex