I want to do a thorough cooling system flush on my motor to get all the rust and acumulated crap out of the engine cooling system. The motor is fully assembled SBC sitting in an engine cradle on the floor on casters. It is much easier and far less messy to do it before I put it into the car for sure.  Don't want to put it in the car and have all the cooling system crap wind up in the radiator when I flush it.Want to hear from people that have done it, what they used to do it, and how good it worked. Been reading up on it on the internet and there are a number of products that have been used from Evapo Rust for Cooling Systems to 420 CF to Citric Acid solution and others.                                                                                                 My I plan is to take out the thermostat, drain the antifreeze flush it with water and fill the cooling system with the cleaner/derusting solution, join the upper and lower rad hoses together with plastic PVC pipe or muffler tubing and hook up a small electric motor with a belt to  the water pump to circulate the solution through the motor for a a day or two. Then drain the system of the flush solution and flush it clean with water before I put in clean antifreeze.