Replacing a heat pump outside unit is a bit more involved than just matching the outdoor coil airflow rate. What's the indoor setup like, what kind of a coil/air handler is there? Is the P/N you gave the new system's or the old system you're replacing? Bryant bills their 650A heat pumps as PURON® REFRIGERANT systems. So, it's R-410A. Since I'm not sure what replaces what, just make sure the old lines are adequate for the new refrigerant if its type is going to change.
400 CFM (cubic foot per minute) is usually referred to as a "ton" capacity of an air handler. Since you're talking about an outside unit, they are normally rated in "BTUs removed" and the same ton on the inside works out to be 12,000 BTUs removed on the outside. So, if you were to rate the Bryant 650AN042-D unit, in which 042 stands for 42,000BTUs removed, in "tonnage", it would be a 3.5 ton unit.