Oh wow, I thought that you wouldn't want to touch anything that wasn't in the public domain. Though I doubt any authors and publishing houses from the 1940's are going to crawl out of the woodwork and cry copyright violation any time soon.
Also, if you convert PD books, does that mean you are within your rights to sell them? Or at least accept donations for your work (I imagine it must take hours on end to type out a printed book).
You can easily publish and sell ebooks on Amazon, and you get a 70% royalty payment for each book sold... Unless they are in the PD, and then you get nothing.
But that doesn't necessarily stop you from selling them on Amazon, as there are many PD for sale on there already. It makes me wonder how they got around Amazon's policy.
The only time Amazon allows you to profit from self-published PD books is if you have added a major original contribution, such as an annotation or something to that effect.