When I installed my safe (900 lb 74" x 48" x 28" ) we used a heavy duty 2 wheel cart that I rented.
I was able to remove the door ,it weighted 400 lb I think.
4 of us roled it in the front door and in to the bedroom .
I had allready poured a footer in the crawl space and blocked up the floor to take all the weight.

I recomend puting the safe as close to a suporting wall ( under the floor) as posible or if over a crawl space build a suport under the safe.
I have seen saging floors from safes set in the middle of a wall.

Johnch