Rusty water jackets. Engine sitting for 7 years

Several years ago, I was advised by a fellow car nut to use Borax. I don't even know if they make it any more. It used to be in the same section and laundry soap. I mixed it in hot water, poured it in the thermostat hole (all other plugs and holes blocked), let it sit for a while, opened side plugs and rinsed with hose under pressure through thermostat hole. I did that several times, and I got a BUNCH of stuff out of it.