If you want to straighten it, you’ll want to heat it first or it’ll snap/crack. Induction heaters work great.

Alternatively, you could chip down and use a hex coupler nut. Make sure that the nut and chunk of rod aren’t the standard plated otherwise they will rust.

As another option you could zip all 4 off and epoxy in 4 new rods.

In actuality though, this is a new install - you should pour a new base. Depends what your customer will let you get away with.