Here's a little more detailed response I got from Andrew at S-B:

"While that model is really old, the engineering of it was done so it fit somewhere between our B212 and D412 pump lines. Our B212 pump can use a 1/2 and 3/4 hp motor and will deliver 1.7 or 2.6 cfm respectively. The D412 pump can use a 1 or 1.5 hp motor and will deliver 3.9 or 5.9 respectively. It was not designed to hold up to the D412 pump, so I don't think it would be a good idea to add too much horse power. You might get away with putting on a 1 hp motor, but as I said, we have no records of that pump anymore so even that might be too much for the pump to handle."

Thanks!