This link has lots of information about your 4-speed transmission, the SM-420.
www.novak-adapt.com/knowledge/transmissions/manual/sm420 It has the gear ratios written (to one decimal place) and you can see there's quite a jump between 1st and 2nd (that's why you say it's short), but less of a jump between 2nd and 3rd. As was stated, in most cases you can start out in 2nd.
Installing an Overdrive transmission, such as a T-5 would get you going faster and slow engine rpm -- and there's lots of stuff on the internet about that swap -- but that requires changing the rear axle as well... All of which is probably difficult and expensive to source in France.
Or you could just enjoy the slow lane and drive it as is.
Good luck!
