Flushing Engine w/o radiator

Im tryin to flush the water inside the engine. I know there is alot of gunk built up before. but the thing is , I just bought a new radiator and tossed the old one. I dont want to run all that gunk and engine flush through my new radiator. anybody have any ideas on how to flush without a radiator?

I had the same idea when I installed my GDI 3 core rad. I took the thermostat housing and thermostat out, bent the lower raiator hose down and put a 5 gal bucket under it, stuck the garden hose where the thermostat housing was, and filled the bucket a few times until it cleared up. Might as well put in a fresh thermostat while your at it .