The boost isn't the problem, it's the 600 ft pounds of torque and the stress from the blower that will cause the mains to fail. You talk to anyone that has built a blower motor, and they'll almost all say the same thing, a girtle is a must with a small block with that much torque.
Unfortunately, you shouldn't of had it line bored, or any machine work done till you had everything needed for the build. Studs and a girdle is something that I wouldn't leave out if you want the engine to last, and if the girdle is installed correctly, you'll need to have the top of the caps machined to match so you can pre load them when the girdle and main caps are torqued down.
There is a lot more to a blower motor than people realize, you'll find yourself redoing some things as you go.
One other thing you'll have issues with is cooling, an Edlebrock water pump and a set of aluminum heads will be the best money you can spend.
