I have 2 approx 1000 lbs safes.
Gotta tell you about my moving them.
The first was put in the back of my pickup buy the guy that gave it to me with his loader. It needed to go down the bulkhead into my cellar. Sounds like your situation.
When I got it to my house, I backed up to the bulkhead, and placed the planks in place right up to the bed of my truck. I put a chain across the front of the truck bed into the 'staking' holes of the bed and a 'come-a-long' was attached to the chain and a chain that was wrapped around the safe. It was winched down the planks and when the length of cable ran out, we cinched it up with another chain and the 'come-a-long' was repositioned for another go.
My brother and I did this and we always stayed above the safe as it went down. I was nervous as heck and only relaxed after my bro said, "Hey, what's gonna happen? If it gets away from us, goes down the ramp and takes out the door casing or busts the wall in the cellar, you'll be pizzed but after a while, you'll think back on it and laugh like Hell about it."
He was right, we couldn't get hurt the way we were handling it, we made sure if that..only the house would suffer a bit.
About five years later, we reversed the process when I moved. Up the stairs it went on planks and into the truck. I had a tractor and loader then so when I got to the new house, I carried it around the back of the house to my walk in cellar and set it in the doorway. That was easy.
The second safe was acquired when my boss said that we didn't have any use for it at work and it was available to anyone who would take it away. There was no one there who could/would so I 'volunteered'.
I got my flat bed car hauling trailer, backed it up to the porch of the building where the safe was. My sons and I levered it out of the building after setting down a plywood 'path' thru the office and onto the trailer and laid it down. Pretty much the same on the other end when it went into my walk in cellar. That was a piece of cake.
I had fun, if you can believe it, moving these things. I always get a sense of satisfaction in doing something that most would consider very difficult. Like this and recently cutting down two 100+ foot tall pine trees within 20 feet of my barn! That's another story !
It does take a LOT of advance thinking about how to do it and how to do it SAFELY. Sometimes it takes equipment too. I'm lucky that way as either I have it or someone in my family does.
My stories aside, if you are putting it in your house and don't have equipment or someone who can assure it will be safely done, get a pro to do it.