You will need to remove the dist, and pull the distributor (and oil pump!) drive gear out, and replace it a tooth or two in the direction you need the distributor to go. Replacing these is sometimes a pain - because it turns as it goes up and down, and the last 1/3rd of an inch where the flat end engages the slot on the oil pump rarely if ever meshes - so you sort of need to gently push it down while turning the engine a little until it drops the final amount.

Actually, thinking about it a couple of seconds more - you really don't even need to do that. Sometimes those gears are a pain to get out (they develop gunk on the lower portion of the shaft which won't easily slide up through the bushing). In any case a simpler thing to do is just swap the plug wires around on the distributor cap one position, and turn the distributor 90 degrees to match. This will also get the vaccum advance gizmo away from the block and give you plenty of 'elbow room' to set the timing.