It should be straight. It seems to me I had the same problem, and someone said that it was bent by a previous owner.
The tube is easy to replace, it just pulls out of the block. You can replace it with a new tube of the same diameter cut to the correct length.
Here is a picture of Denny Graham's engine:
http://www.pbase.com/dennygraham/image/137589816The tube is 3/8" in diameter, and on my engine it rises about 5 7/8" above the block.
