In Boneyard, Razor is bugged for me.
Most topics involving her are about her being dead, her not wanting to talk to you, etc. Me, I can't get past the first conversation.
After talking to her I should have a holodisk in my inventory. Instead I get nothing, and talking to her again repeats the conversation as if we've never spoken before.

Now, I've tried talking to her first, talking to Zimmerman first, leaving town and coming back, it's the same every time.
I've also tried installing older bug fixes, but those tend to crash the game and/or break my savegames.

Is there a fix for this? Or failing that, maybe a way to cheat that holodisk into my inventory so I can force the quest to advance that way?

If I remember correctly (it been more than 10 years since I played it) this quest is bugged. Unfortunately, a lot weird things happen during this quest. Before speaking to Razor, have you killed the death claws & get the gun runners to help? If you do that, the dialogue with Razor will change.

Yeah I killed the Deathclaws and got the help from the gunrunners. It opens that path of the quest.
Telling Razor that I want to try to talk to Zimmerman first gives the same bug though; no holodisk.
It also brings back another old bug where after I enter town, there'll only be her legs standing there when I come back.

The reason I want the disk is to go the solo path of taking out the Regulators, so I'll have an easier time keeping Miles and Smitty alive. It's a shorter distance from Zimmerman to Miles then it is from the entrance.

In the meantime I'm trying to clear Adytum with (at least) no named characters dying during the attack. Maybe I'll get lucky.

Well, good luck! I don't think I can help you in any way. The only thing I can remember, is Razor explaining you who killed Zimmerman's son and then hands over the evidence. As to why it doesn't happen this to you, well, I'm out of ideas. BUGS!

On an off chance that this helps: with Fallout Fixt 0.81Alpha, the "I'll just take care of the Regulators myself." option does not give me the disk. But from the same point in the conversation, asking about Gun Runners, then saying "Okay, give me the holodisk, and I'll go talk to the Gun Runners before I approach Zimmerman." does. At that point I can still "take care of the Regulators myself" instead of actually talking to the Gun Runners, though.

Here are the full conversation paths (depending on whether you have / haven't talked to Zimmerman first) that gives me the disk:
[spoiler]
"Are you the leader of this gang?"
"Zimmerman sent me." / "If you're not a gang, then what are you?"
"To pay you back for killing his son." / "Defend yourselves from whom?"
"Uh... who are you going to send to hell?" / "Zimmerman's Son? Why would they kill him?"
"Why would the regulators kill Zimmerman's son?"
"They killed him? What did he do?"
"Why haven't you given this to Josh's Father?"
"Why don't I give him the disk?"
"Sure. Anything to help."
"Well, where are these Gun Runners? Why don't you get some weapons from them?"
"Okay, give me the holodisk, and I'll go talk to the Gun Runners before I approach Zimmerman."
"See you later."
[/spoiler]