In the draft of the script I have from October 1993, the opening scenes on the Enterprise-B were supposed to feature the ENTIRE original cast. They gave Spock a joke on the first page that seems out of character for him - Kirk & co. are all crammed into a turbolift and Spock says to Bones "I haven't felt this close to you in years." Seems more like a line that Bones would say. There's no Demora Sulu, either. Bones is given the teasing line to Kirk after he says "Take us out," getting the Ent. B on its way.
By the time they start dealing with the Nexus, Spock quickly falls back into his science officer role, asking to perform analysis from the Ent. B's SO. Scotty goes down to engineering to work on the warp engines for a maneuver after the first refugee ship is destroyed. Bones enlists Chekov as his nurse when they beam survivors aboard. Uhura assists the lieutenant attempting to beam the survivors aboard. Sulu takes over for the Ent. B helmsman after he's killed when the ship is hit by the Nexus. Bones does have the quick scene with Guinan in sickbay.
Following the Ent. B pulling away from the Nexus, Uhura has all the lines about the status of the ship (given to Demora in the final version). And then it's Spock, Bones and Harriman discovering the forward deflector room has been destroyed.
And, finally, this is how the last 23rd century scene played out:
36 INT. ENTERPRISE-B - BRIDGE
A short time later. Chekov, Sulu, and Uhura at their
positions. Spock, Harriman and Bones are standing near
one of the aft stations, listening to Scotty, who is
also on the Bridge.
SCOTTY
I've checked the entire ship and
the surrounding space... there's
no sign of him.
A silent moment. Bones looks to Spock, hoping to hear
some sort of miracle.
BONES
Spock?
Spock takes a moment... looks at the empty command
chair.
SPOCK
There is only one logical
conclusion, Doctor.
(beat)
The Captain is dead.
A long beat as everyone is forced to accept this
terrible truth. Spock sits down heavily at the science
station.
BONES
(quiet)
Just a quick... run around the
block...
SCOTTY
I never thought it would end like
this...
Spock turns away from them all... lost in private
thoughts.
SPOCK
All things must end, Mister
Scott...
Bones moves to Spock, and the two men share a very
private moment. Harriman finally breaks the stillness
of the Bridge.
HARRIMAN
Let's go home.
Sulu works the console and Harriman goes down to the
Captain's chair and takes command of the ship.
Spock and Bones exchange a final look. Off the
reactions of these two friends who've just lost someone
very dear to them both...
All-in-all, most of the original version shoehorned in the original characters. Uhura is barely given anything to do, basically the same with Chekov. Most of them were boiled down to cameos.