Cleaning out a cast iron block

I'de pull the most accessible freeze plugs. You'de be surprised what can hide at the bottom of a block! When I had my Dodge conv. van with the 5.9 I had a freeze plug start to leak (rusting from the inside out). I pulled all the plugs and flushed the block from the front to back and back to front. Installed the new freeze plugs and fresh coolant. That alone dropped the coolant temp about 15 degrees. After that I installed a new radiator and fan clutch and it again dropped a bit more. The engine always ran about 210 when I got it. After all that even when towing it took a lot to get it to break 200 deg.