If you pull the seats and remove the console (assuming you have one), you will be able to get it out of the car as it is not that big once out from underneath the dash. Be aware that it will leak ALOT as the heater core tends to retain a fair amount of coolant. I recommend 2 things
1. once you pull the heater hoses, stuff a rag into the heat core tubes and tape over. You might be able to get some caps that will fit through the firewall but in my experience they usually pops off as you pull the heater box through.
2. cover your floor/carpet with plastic (assuming this is or will be in the car), if not disregard