I have a Holley 750 carb. on a 454 mag. I have an electric fuel pump hooked and regulator. I know how to adjust the floats, just wondering do i leave the fuel pump running when i take out the plug sites, and is there a marine pressure gauge that i can hook up to the regulator. The pump, regulator are both Holley products. Thanks

No you don't need the pump running, let it idle a minute, shut it off and remove the fuel level plugs ,adjust as needed, restart and check again,
there is a Marine pressure gauge available, I run one on each engine, I set my regulators at 6 psi.

McDaniel all stainless gauges are very high quality

Thanks for the help, i will try these two. I will look online for the gauge.

Hardin Marine may have them