Before doing anything I would remove the thermostat, remove the upper radiator hose from the radiator. Using a garden hose, while filling the open end of the upper radiator hose with water, watch the amount of water and clarity that comes out where you disconnected it. If there is good flow coming out, should be equal to what is going in, then the radiator is probably fine. If not I would add some Dawn or Cascade and let it run - connect the hose back of course. After about 15 mins at operating temp, let it cool and drain the system. Repeat the above steps and see if the flow has increased. If not, new radiator time. Remember to install the t-stat when finished.
If you go to a new radiator, get the 2 core instead of the single core. Change the lower hose, dump that quick connect nonsense connection at the lower hose and use hose clamps. With all the crap that was in your system, you'll pay hell getting the hose off. I just cut mine and replaced with new.