Put me in the rinse it out and run it camp.
Vinegar does work great.
Flush the block and radiator both (back flush) the radiator.
I used a section of 3/8 steel trans cooler line with a 90 in the end hooked to a water hose and just chased the loose crap out.
Then did the two day vinegar soak after it was all together and running.
That motor was way worse than yours in the block, and years later still has bright green coolant.
