How many people are you feeding? Unless you're feeding a crowd, I'd suggest cutting it into smaller, more manageable pieces and freezing what you're not going to use right away.
Without knowing what cut it is, I guess you'll need to experiment, since different cuts do best with different cooking methods. I'd use something that I know the weight of - like a soda bottle or some cans of food - and cut two pieces that size. Sear one and cook to medium rare, braise one and cook to well done, and see which works out best.
Hope this helps.
Anyplace where people argue about food is a good place.
~ Anthony Bourdain, Parts Unknown, 2018