I pull the stat, put the top hose/hsg back in, and flush from the lower and top hoses.
Wouldn't hurt to flush the heater core, too.
As for coolant, I use RMI 25 and tap water. [Some use distilled, some say not to]. In the winter, I add just enuf antifreeze to cover the low temps. It comes out in the spring.
I get the RMI from Nick Micale @ AZ GN
W/ a new rad, I also drop the engine cooler lines and the trans lines, and flush them w/ carb cleaner. That way, any
in them doesn't go into the new coolers.