Welcome to the Team!
Back when I was running (and blowing up) a 409 regularly no one wanted a truck block because of the notch in the block the kills compression. With today's gas quality a Truck block is ideal as it allows a lower compression than obtainable with a car block, with the added bonus of a truck block being tougher (more nickel added to the cast iron to make it stronger and last longer). The car and truck 409's all look alike on the outside, unlike the newer Mark IV BBC engines that actually used a taller block to hold an extra piston ring on their truck blocks.
Best of luck.