I put it into gear and it dies.
Don't worry about the dist. if it has enough movement to time it. That is, -- If it will run and has the "swing" (rotation) to time it, it's OK. The slants don't have much distributor movement. If you are unaware there's the clamp bolt at the block, which gives you a small amount of dist. movement. If you need more, that same piece of the clamp goes back around the bottom of the dist. body, and there's another bolt into the bottom of the dist. which works just like the one on the block.........you can loosen it and move the dist. more.
Make sure you have the timing light dialed to zero. If possible, use a NON dial up light and read timing directly off the timing marks. Make sure of course that you are on no1 cylinder--the front most cylinder.
Did you ever check that the mechanical/ centrifugal advance seems to be OK? Just spring the rotor against it's springs and "feel" for slop and "feel" for free movement. You should be able to rotote the rotor against the springs and it should snap back freely.