I did a road bike conversion like this with a super tall stem so that I sat bolt upright.

The first thing I can recommend if you do this is a sprung saddle. You get a lot more road shock up your spine when you sit upright like that. My back hurt after the first five-mile ride (though this was pretty extreme--I used a tall stem and a stem extender, wanting to see how tall and upright I could get).

I never had a problem with popping the unwanted wheelie. However, when I first rode it after setting it up, the handling felt very strange (like a long wheelbase recumbent, if you've ever ridden one). The steering was super light, very touchy. It really surprised me when I first climbed on. However, I got used to it pretty quickly (like, after one mile).

I saw a thread once where somebody posted a photo of a "conversion" like you are describing, and he ridiculed it, saying that it was a waste of what the frame was designed for--which amounted to, essentially, a lower and more forward CoG, plus the greater relative power resulting from the tucked position.

But life is not all about looking at the top of your front wheel.