Clean radiator, cool engine, coolant PH, flow, fans, shrouds.

Good writeup. Before changing a failed radiator (leaking), I drain and fill w/ water and Prestone SuperFlush, which I recall is a citrus product (acid, like yours). I use the old radiator as a filter to catch the junk. If easy, I remove the block drains. A lot of crud comes out and you often need to use a screwdriver to free them up. As you, I put a screen in the top hose when installing the new (or cleaned) radiator to catch chunks. 99 Cent stores sells a set of kitchen drain screens that I remove the border from the smallest one. I run pure water for a day or two, then flush and fill 50/50 using distilled or "purified" (de-ionized) water. When I have seen the cooling passages in a block after this (head off or such), it looks pristine. Citric acid is used to wash flux from circuit boards, so must work well. You could go to the other extreme in pH and try TSP, but it removes paint, so might attack gaskets and seals.