Generally speaking, go for a stiffer nib as you are going to be pushing rather than pulling. Stiff nibs suffer less ink starvation when pushing. Also use a quick drying ink to avoid smudges like Noodler’s Bernanke.
When i write lefty i use a very low elevation and have no problems. I have a friend who’s lefty but writes like he’s ripping open a box with an X-Acto knife. He has broken one of my pens with the way he writes.
Take a look at the Pilot Kakuno I recommend in another comment. It’s actually designed for Japanese children to introduce them to fountain pens (hence the variety of colors).
I’ve had a Yellow Lamy Safari on me for 9 years, carried with me every day!
Its the best $35 fountain pen ever!! I swear!
I even mixed my own ink color by mixing Some Lamy Green with Lamy Black.
Its also one of the only fountain pens with two line-weights When you write on the regular side it’s thick, when you write on the top-side its half width which comes in hand when sketching or writing small notes. ****