You don't have to remove the intake. Use two longer bolts to replace stock intake bolts diagonally positioned front and rear. Even easier when you use an engine leveler. Carb plate works well too. Just make sure it's bolts tightly to the intake. The tensile strength of the 3 carb bolts is many times greater than the required lifting force and engine weight but you don't want to induce side loading on the intake carb flange by not using the plate. Flathead engine weighs about 545 lbs.
Check out the Proof Load ratings in this chart.
https://www.engineeringtoolbox.com/u...ad-d_2066.html