Slant 6 Turbo 68Dart Project

Well today I gave up on trying to figure out my overheating symptoms, and decided it's time to ditch the radiator for a new one, so I ordered a new aluminum rad. I feel whoever had the car before me was running straight water, rusted the block up pretty good inside, and then all that junk got flushed into the radiator, because it was cooling just fine for a year or so. I tried literally everything to no avail. I can drive the car for about 15 minutes before it goes up to 220 and it keeps climbing if you let it. So I tried flushing the rad, taking it out like you guys saw a few pages back, and just can not get it unclogged. Rad shop wanted $80 to deal with it, and MAYBE fix it, or $150 for a new one. The choice was obvious.