Sizing turbo for slant 6 powerwagon

Hey guys I'd like opinions on sizing a turbo for a slant 6 75 dodge w100 paisa wagon club cab short box, It's gonna be stock internals, 4 barrel intake, holley 500cfm 2 barrel carb converted over to draw through, and 33" tires with 3.55 gears planning on going 4.10's later down the road. I have no idea on sizing this beast of a truck. My old man tells me a turbo and wastegate from a late 80's Buick GN 3.8 will be ideal. But I'd like other opinions before I grenade and blow my *** sky high.