Where I'm from no one burns oil for heat or even has basements. So I'm not familiar with basements and their layout.
Lack of knowledge or experience doesn't disqualify one from offering a suggestion here does it?
Al's suggestion of a ramp down the stairs and some type of pulley system (if you have something to attach to) might make the the job a little easier and safer.
If you have any mountain climbing friends you might borrow a couple of prusik pulleys and with two prusik hitches to make this 3:1 pulley system. The prusik hitch will slip against the pulleys but hold if the pulling line is released, I think.
http://www.adventuremotorcycle.com/spotlight/news-archive/19-spotlight/news/600-news-bestrest-motorcycle-recovery-system#.VKIVGDAASeems like if the new tank will fit coming down to the basement, the old one should go up. i would not want to cut it up in basement.
Floyd