You manual should say otherwise it you may have to take your serial number to a dealer.
You need both the flow and pressure spec to calculate hp. The more of either the higher the hp will be.
Snow blowing is like brush mowing, more is always better until you break something.
But on the other hand snowblowers were made for 743 with a smaller pump then yours. Regardless sometimes it will do more then you thought possible and other times it will feel a bit underpowered. Thats the nature of hydraulic drives, they really let you see how big the load on the attachment truly is.
The good news with a skidsteer is it is easy to slow the wheels down.
The other part of the equasion is the blower motor needs to be sized to the hydraulic pump volume to get the best rpm of the blower. If you get a second hand blower make sure it come off a machine with simular flow as yours. Say + or - 2 gpm,
Ken