If it really needs replaced, just go get a cheapy aluminum one from a chain that has locations in the general region(s) you will drive.
Real radiators (as in OEM copper/brass) are either unavailable or ridiculously expensive. Recoring copper/brass last I checked was $500.
The aftermarket "performance" AL radiators outside of mishimoto are not nearly as trouble-free as they should be for what they cost.
The parts store cheapies will likely either fail immediately, or give you decent life. As expensive as antifreeze is now, I'd probably not flush the block until I had replaced the radiator and ensured it wasn't going to leak that new antifreeze all over the ground. At least if it fails, with a lifetime warranty, you can replace your $100 radiator in no time at all if purchased locally.
The one downside is that you STILL (how long have they been making replacement radiators for our trucks now??) need to ensure that it fits as it should, and that there is no metal to metal contact on install. I noticed mine wanted to rub on the upper brackets, I just put a strip of old bicycle tube over those spots before I tightened it down fully.
Edit: FWIW my parts store cheapy has lasted four years thus far. It doesn't get driven much however. The first one failed as soon as I started the engine. But being a parts store piece, I took it in and no questions, they replaced it.
