I actually don't know about that. Since naturally things get faster as they move downward. And seeing as you were moving at 75.10 prior to the launch, I can't see how letting gravity do the work for a record would cut it.
The high the object, and the weight of that object, with the default -9.82 would have it moving fast if it was falling from 278 height. (Sorry, you can do the math yourself. I'm not feeling very algebra right now)
Personally, I don't feel that's going to cut it as the record, but the throw is pretty legit, and congratz on that.
I'll add that in the morning.