So my wife decided she really likes bike riding this summer, just on the road. But all she had was a pretty low end mountain bike, bottom line components, and she constantly complained about it. So I found a 48cm 1990ish Peugeot Nice on craigslist that needed some TLC and bought it. A month later it's almost done, shined up really nice. I believe this frame is racing geometry, feels really light and lively. I love it, but it's too small for me. But my wife just told me she wont ride it with the drop bars. As much as I hate to do it I'm thinking about putting a more upright stem on the bike along with some mountain bike style bars.

So my question for all you guys out there with a ton more knowledge than me about riding position and frame geometry; will this just ruin the bike? Or should I go ahead and attempt it.