Will the front drum spindles from a 70 chevelle work with the disk brakes?

no some people say you can modified them to make them work

yes, after you cut off some of the top mounting boss area where the top bolt attaches. Go to the disc brake conversion archives on this site and search. I just milled mine off a couple months ago. If I recall correctly, my machine shop cut off .60 of an inch so the disc brake caliper braket will bolt to the top threaded mounting hole. But in hindsite, this is not rocket science, and you could cut off that boss with a hack saw, and grind it the last few thousand of an inch so you can mount the caliper braket square to the spindle. There should be photos of the disc and drum spindles before and after the cut. I think I may have photos I could email if you wish. Don't spend a hundred bucks for disc spindles on ebay as I suspect most are just milled down drum spindles.