Just an thought. I had a 460 in a jet boat for 10 years. Start boat out side water with hose or back trailer into lake (best) . Start and idle. I always had my regulator set at 6.5 psi for a 4bbll carb. Check your carb spec by calling Holley.
You should be able to have someone run motor up and you view the fuel sight glass to make sure fuel is at the right levels. And watck your fuel pressure, it should stay the same.
This may show you a little whats happening, You may be running low on fuel when you step on the gas.
Also, slim chance, you may still have some water laying in the bowls.
I know technology is king but I still like the mech. fuel pumps.
I have seen many strange things happen to MSD boxes and ign. systems when your voltage drops below 9v-10v for some reason.