Can I convert a roll up garage door to a side-hinged door?
A hinged garage door puts a LOT of stress on the structure - they are heavy with a long lever. Compare to a vertical-lift door (any style) which is basically a straight-down load.

Do you have 6x6 or larger posts on both sides of the door? Are they in good condition and firmly attached to the rest of the structure?

Check the swing area of the proposed door - is it over a good surface? Pavement sloping away from the garage is best, flat gravel or grass are not good, anything higher than the bottom of the door is a deal breaker. Does it snow where you are? 

I would suggest replacing the up-and-over with a rolling door. Just so everyone's on the same page, when you say up-and-over I assume the door is one piece, and swings up on 2 pivot points becoming the ceiling over the parking place. A slide-up door is in sections about 50cm high and ends up in the same place as the up-and-over, but it's on tracks and the tracks can be higher up in the garage as needed.

A rolling door can be mounted completely external (indoor is better, but...) to the garage, as high as you need. No space is needed above the parking place. They're not all that cheap, and you can't build one yourself, but they are very easy to install and won't pull your vertical supports out.