19 lbs should make 375 hp.
I have 19 # injectors on my stang and they work well. I had 24# injectors the car ran rich and stunk of fuel. The mods Edelbrock intake, heads, 2.02/ 1.90 .545 lift, bored 30 over, MSD ignition, and so on. I don't race so others would say go with the 24#. To little fuel is more dangerous than to much. Starve a motor of fuel, tached out, baboom!! If its a daily driver with basic mods, 19# work. Occasionally I beat her and things are fine, good luck. One more thing get a good fuel presure reg. I run my a hair under 40lbs.