89build66

Anyone know a way to use superflush on an 89 Cherokee after the old closed system radiator is out? I’ve noticed a lot of rust buildup and have all my parts for converting to the open system (my personal preference) In hindsight I probably should’ve flushed it with the old radiator before I took it out. Now I don’t want all the crap going into my new radiator. I’ve reversed flushed the heater core and the engine block with tap water until it’s running clear, but there still rust deposits in the passages I can see. Any help would be appreciated!