The heater core should not make much of a difference. Lots of Mopars shut the flow off on that circuit with the A/C on.
The bypass circuit on the LA engine is huge compared to other makes. One of the reasons you can block the heater flow without issue.
You have very little heat to get rid of, and a huge radiator. In the winter you may need a bit of cardboard if it snows where you are.
When you open the system to add the heater core, drill a 3/32 hole in the thermostat in the flat part near the opening. This creates a small flow past the thermostat, and makes the system easier to fill too.
B.
