I'm thinking you're working on a Trike or similar to need this sprocket to fit on your axle/jack shaft?
I looked into the Grainger site. Search the part numbers in the pics below. I may be wrong but that bushing is supposed to bolt on to that sprocket. Al least according to the sprocket it needs that bushing for a 5/8 yes I only see two holes too. Then you'll need a #40 chain. And it's a 45 tooth.
Oh. And that sprocket is expensive.
But with a drill maybe if you get two of those 8 dollar bushings and sandwich a 44 tooth bicycle sprocket in between,line it up straight and drill the holes it may come out for you.