I know that the 747-300 tail height is 63'5", but how tall is the fuselage alone? Also, what is the height of the cargo area and main cabin?
The minimum and maximum height is depicted as dimension "A" (with hump) or "H" (without hump) on the infographic below from Boeing's "Airplane Characteristics for Airport Planning":
(747-100B, -200B, -200C and 300 dimensions)
Boeing's ACAPS documents are handy, but they always provide ranges. Moreover, the 747 doesn't sit flat on the ground; it has a slightly nose-down attitude, so that aft doors are higher than forward ones. If you wanted something more of an absolute reference, I can tell you this:
The 747 fuselage is 309 inches high from keel (WL 91) to crown on the humped part of the fuselage. The constant-cross-section part of the fuselage is a 256" wide, 268" tall cylinder.
- The cargo deck is 27 inches above the keel (WL 118).
- The main deck floor is 109 inches above the keel. The top of the main deck floor is the reference height for the entire fuselage, and is WL 200 (waterline, 200" above the imaginary zero)
- The upper deck floor is 217 inches above the keel (WL 308).
By keel, I mean the bottom of the fuselage proper, excluding the wing-body fairing underneath. That would add somewhere between 5 and 11 inches below the keel, approximately. It's a lot harder to find precise measurements on that part of the plane; Boeing doesn't consider fairings and protuberances when describing dimensions.
Source: Boeing 747 Structural Repair Manual (SRM).