ONE + TWO + FOUR = SEVEN

In the equation above, each letter represents a digit. Determine the value for each letter.

(If ambiguity exists, let later letters , i.e. "W", be greater than earlier letters, i.e. "U".)

Source: Original.

Solutions were received from Arturo Pascalin, Bill Beall, Philippe Fondanaiche, Joseph W. DeVincentis, Denis Borris, Carlos Rivera, Robert T McQuaid, Alexander Doskey, Radu Ionescu, David Betanzos. There are only 34 valid solutions, 8 if you don't consider leading zeros. When we limit W>U, those 8 become these 4: 
ONE  +  TWO  +  FOUR  = SEVEN
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350     683     9372    10405...smallest "seven"
530     645     9528    10703
630     546     9627    10803...largest "seven"
940     739     8925    10604
Depending on the order of application of my "ambiguity rule" various solutions can be singled out, so I just left them all in the list. (For example, if F is to be smaller than O, then the last solution is best, but if V is to be greater than most, then the third solution is best.)

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