Well, first off congrats. You've got a basement
The whole setup is up to your imagination and personal taste.
But what you really have to consider are following things, like;
How is the dampness in your basement? Do you have floods? Are the gutters in good working condition?
You should apply epoxy waterproofing to the walls if not already done. You should also get one or more dehumidifier.
How is the illumination?
You don't wanna work in a dark, dingy corner or enjoy your collection with a candle in your hand
Do you have windows?
Are they safe? You might have to get some metal bars for them.
How is the cooling/heating?
Most basements get cool in the summer- but really cold in the winter time. Make sure it's a proper temperature and the dampness is not too much.
How secure is the entrance door?
Is there one or more doors? Who has access to the room and how (key, electronic, biometric?)
What other work do you plan on doing?
Do you plan on welding in your basement or just maintenance work?
I still would put a safe in, just in case. For handgun storage/display I would get some glass display counters (like in a gun shop), just with access from the front. So you can put them on the wall...
I also would get a surveillance system as well as adequate insurance protection.
Have fun building it and keep us updated