Kinda looks like the stuff I was getting up last May, just much worse..
It is a gunk, very red in nature.. sucks. It gunked up everything, infact.. my oil cooler is clogged from coolant flow too.. everything I'm doing is brand new. I had the engine disassembled and hot tanked, lapped, coolant plugs changed, blue printed, head work, resurface and HG installed at the machine shop this time.
I fear this was due to a very small leak in the headgasket under 10+ psi of boost. My temps use to hover around 200-210 degrees... to high but it could be maintained. Eventually it would overheat, but the coolant just got worse. I flushed it many times.
I hope this is not the case for you, but it looks very alike. I would imagine you do have a bad headgasket issue. Have you done a leak down test and compression?
I'm sorry if you posted you have, but this thread is long, haven't read it all haha.