Please guys don't mess with your rad.
You mess up your rad it's $750 to $1500 to for a recore.
Buy a stacked plate or other type of heat exchanger. Plumb it into the heater line with a bypass and your done.
I covered that topic in my thread "hydronic heating in a bus".
Around here, the rear engine buses are the ones that have the 12 volt coolant booster pumps.
Only a few of the front engine buses have one.