I need to do this too. My door window channels are completely rusted out. The brackets appear to be good and can be cut off of the channels and welded onto the new channels. I found new window sash channels at Steel Rubber. The originals appear to have been chrome plated from the factory in my ’62. Let me know how it goes for you. I believe the Buick Skylark from those years has parts that are interchangeable for this as it was also a two door hardtop. I’ve never done this, but it doesn’t look too difficult.