Does the Mustang have the same fuel interruption problem during negative g?

absalutly not only the first spit they made has that problem l have the spitfire 14 and its realy nice handles smooth ive flown a few mustangs my friends have they are real nice l have the five pointed prop witch is better for alt and helps with 0 grav so get a five point prop if u are still worryed

Well the other answerer, l umm..doubt has flown an F51.
The problem you're talking about has NOTHING to do with the propeller. The Spits Mk I-IV had carburetors instead of fuel injection. In negative G situations the fuel would splash out of them, stalling the engine. By rolling first, the pilot actually threw the fuel into the intake manifold.
By the time the RR Merlin was used in the P51B, the current issue Merlin was fuel injected. (It was mechanical fuel injection btw, much more primitive than the fuel injection system in ur car today.)