I use the exact same carburetor on my 455 up near 600hp. It was also used on 3 previous engines that were in my car and has been flawless the entire time.
https://www.youtube.com/watch?v=6zVdoLR-VzMI have done a LOT of testing and on several occasions the engine "puked" on full throttle starts with the following set-ups.
Installing a K & N X-Treem lid
Installing an RPM intake and shorter air cleaner
Putting a full open spacer on my factory dual plane intake
Installing a Performer intake on my current engine
The Performer intake has very restrictive runners to feed nearly 600hp so the engine hated it.
My carburetor is not "modified" in any was far as grinding or "porting" it anyplace, it is basically a stone stock part recalibrated for exactly what I am doing.
It uses the exact same parts we sent you for your carb except for jets and metering rods.
Hanger is an "L", and we change metering rods based on weather conditions at the track. The metering rods are all custom machined from the same cores for very precise metering changes.
I suspect a fundamental issue someplace not related to the carburetor. This assumes that it is completely/correctly rebuilt with correct settings and nothing plugged up anyplace internally.
If you can't find a suitable replacement we test carburetors here for $35 plus the fuel (usually about $15)......Cliff