It's marginal - I have 3" schedule 40 in my tower and it sags when I raise it. Not to a worrying extent, but you are talking about a much taller tower than mine...
Can't beat the price - so I'd consider spending extra money on guy wires to steady it, plus lots of lift wires if you want yours to be tiltable. Don't forget you need a gin pole at least 50% of the tower height and of roughly the same size. Considering that, you could use 40' for the tower and 20' for the gin. Now you've got a better match between the tower size and the materials. I am assuming, of course, that you are talking about steel (there is such a thing as schedule 80 aluminum after all).
WT to go on top, maybe 6 feet max or so...
All off the top of my head. I always say that the loads that make towers fail are the dynamic ones that are hard to figure out. Gotta make your brain sweat over those problems, you can't just mix-and-match a safe product. There's no recipie book for these things, either.