A 50 ton should have 12k or so of line pull, right? You probably could have pushed up against that at least.
A 3” flat sling should be good for about 8k choked, or at least that’s what ours are good for, so two gets you to at least 16k.
We had a set of rope slings made up by Gap Arborist for picking things like that. 25’ deadeye slings, made from 3/4” Ultrex. They’re really light, lighter than our 5/8” Polydyne slings actually, and they have a working load limit of 15k each. You couldn’t break them if you tried, with an ABS of 75k!