[Craig Lewis]

Nice job Tom and thanks for posting the photos.
A lot of crud piles up inside the bottom the water jackets over the years and you probably loosened up some of it.

With the head off my block, I inserted a piece of coathanger down into the jackets and spun it with a drill which dislodged literally handfulls of rust.
I also fished out several pieces of thick, corroded wire....apparently left over from the original casting process.
Then when I unsoldered my radiator bottom tank, I found 10 or 11 tubes plugged solid with gravel, grease, feathers, wood bits and both red & white sulphated powder chunks.
Oh yes....2 radiator experts flow tested it beforehand and said it was wonderfull.
I must remember to rig up some kind of filter like yours when I start driving it.