Overheating issues

Quick update. I went ahead and just hooked everything back up and filled the rad with thermocure and water to help clean out the system. I couldn't get the drain plugs on the block to budge at all, any more force I was about to start stripping the bolt heads. I think I can reach some of the freeze plugs, but two of them are definitely obstructed by the headers. I've planned to remove those to wrap them sometime soon anyway.

Before, I could only get about 3 miles down the road before it'd get over 200. Tonight I drove maybe 6 miles (a mix of stop and go around town) and it never got over 190. Would've kept going just to see but had pizza in the oven :p
I'll see tomorrow how it does on a longer journey but maybe all it really was the radiator afterall.