I like the aesthetic, but aerodynamically, that roof-mounted gurney flap completely negates any aero benefit of the open engine cover/"spoiler."
Also, is this based off of a real car? If someone actually put a 4-cylinder into a 1950s Fiat 500, then they have some serious spontaneity issues. I'd think that somewhere throughout the probably 40+hour process of an engine swap, they would be like "hmm, maybe putting such a heavy engine way at the back is a bad idea..."
Then again, Porsche 911. Sigh.
Apologies for my rambling; I used to like cars, a lot.