Would it be feasible to have a machine shop clean the block for you? That might be the easy button.
Many moons ago, I rigged up a system with an old pool pump that circulated a rust removing solution (I chose strong white vinegar). Inbound and outbound points were the block drain and upper radiator hose. Pump sat in a big tub where inbound and outbound points outbound points were plumbed in.
Disposing of the nasty “stuff” was still a problem.
Does Evaporust “evaporate” when left open? Might be able to let the used solution just sit outdoors in a safe place, and they dispose of the dry remnants in the normal garbage.
