Hi Darren,
Weber float levels are designed for 3.5 psi so thats where it needs to be,...
Emulsion tubes?
Do you have any 135 MJ's on hand?
I would also confirm fuel pump volume to ensure that its able to keep the float chambers full at high demand. You'd never believe what I've found regarding plugged filters, tank screens, failing pumps, etc. You want 1 litre/minute.