Doubtful that the tiles have asbestos in them if they were installed in 1979 and if they do, it would be because they were laying around in a warehouse for several years before that and then would only contain up to 3%. The mastic from that era contained no asbestos. Absolutely no danger of mesothelioma from exposure for tearing up a floor like that unless you do it everyday for 20 years and you grind up the stuff in a blender and huff it through a bong. If you are still concerned about this issue, send me a pm.

If you have a paint gun style heater, you may be able to heat the tiles a little and be surprised how easily they will come up. Then you could put down luann and use an undercut saw on the door jambs.

I gotta disagree with BC on going over it with more VCT--telegraphing would definitely be a problem, and the mastic may actually reactivate the mastic under the existing tiles. Also, I used to buy VCT for $.18/tile and sell it for $.60-$.90.