Rough idle turned to crank then ka-thunk

Time to do some diagnostics. 1st, if the timing marks are on TDC, and the rotor points where it shows in the picture, and the wires are in the cap as the factory installed them (#1 being near the locating tab on the dist) the timing is way off.
I would pull the plugs, and move the damper back and forth while watching the rotor on the dist. See how far the crank rotates before the rotor moves. This will give an indication of the timeing chain condition. Also pull the dist and check the gear. If those look OK, time for a compression test.
I thought slantys did not have chains