I've been trying to do the same thing on my Blazer. Picked up a Curt basket on Amazon which seems fine but my problem is there was no factory rack. I went through a lot of headaches installing a factory rack to mount the basket to, but in the long run those plastic feet on the factory rack just aren't meant to support any leveraged weight.
My next try is a set of Yakima generic Landing Pads (#11) and Control Towers (don't waste your money on the the crossbars - they are standard dimension pipe). The key is installing nut-inserts in the roof, McMaster-Carr has the tool (+/- $20) and Fastenal has a variety of sizes of inserts. Just be careful of where the roof braces are.