High flow are generally for articulated 4WD tractors. Any Spray Coupe I’m familiar with would certainly be a low flow.

Open center vs closed center depends on the hydraulic system that the vehicle uses for the steering system. Looking through parts books or talking to a knowledgeable dealer or technician to see what type of pump is providing flow to the steering system will determine if it is open or closed center. There may be exceptions but generally If it is a gear roller pump it’s going to be open center, if a variable displacement axial piston pump it will be closed center.