Id go get it fixed at a good radiator shop I had one done for the 76 when I sold it and he did a great job and it only cost me 60 or 80 bucks somethin around there.
Oh yeah forgot about the plastic garbage. Get an aluminum one then. I asked the guy that did that radiator how much a new aluminum one for the 85 would be and he said 147 bucks installed.
If the leaks are small you could just patch it with a little JB weld till you get the new one.
Should hold a little while till you get the new one. I plugged a hole in the f750 from a rock from another dump that put a fist sized hole in the radiator it held till we got it back home.
Jumpin in late here and didn't read the whole thread but...I've used the stop leak before, usually the leak comes back eventually bigger badder and worse. So in a pinch or in a vehicle you're gonna sell, use it, don't if you're gonna keep it. You'd be better off throwing an egg in there, and yes that does work. As for the leak, how bad and where from? If it's just a couple pin holes, you could patch it with JB, usually buys you a few months. Or go get it patched up at a shop...usually I get charged between $50-100. If you need a recore, you're better off just buying new.
Yup I concur with the fellas who are against the stop leak. Anytime you put some long lasting particulate in fluid that runs in nooks and crannies (esp. in your intake, through the thermostat, etc) you're gonna get some gum action where you don't want it.
If the leaks are minor and not in the fins (ie. leak in the tank or perimeter) JB weld works but if you're really cool, put a self tapping screw in that sucker lol