It sounds like a fine plan to me. Like non-fixie said, everything you'd be doing is reversible and anything that makes you want to ride the bike is a worthy project.

There's really no such thing as "road bike geometry" in the singular sense, and Schwinn sold a World Sport that I'd bet was the same frame but with drop bars.

Schwinn World Tourist

While it's definitely worth obsessing over bike size before you buy a bike, when you're talking about reconfiguring a bike that you already own I say build it, ride it and see if it's comfortable. "The right size for you" is also something that doesn't really exist in a singular sense. I've had bikes from 52cm to 57cm that I've been able to set up for a ride that's perfectly comfortable for me.