I have a chevy 400 that has a good choke & good ignition and has to be primed every time it sets for more than 3 days. Tiny gas leak in carb bowl, if all the fuel leaks out between cranking it is hard to get fuel pressure up on the starter fast enough to get it to crank. Typically hard starting like this is choke problems or ignition too far advanced. other possibilities are endless--bad plug wires, weak condensor, bad coil wire, bad points setting or condition. If your choke is closing nice and tight in the am I would start looking at plug and coil wire ends for corrosion and battery and starter wire connections also.
As far as tuneing I gap my points about 15-17 thousandths and set my timing at 10* before TDC. i believe book says 6*, plugs at 35. idle about 1000-1100 rpm (warm)--too slow is worse than too fast as oiling and charging works better with a little speed. although a 600 rpm idle sounds wonderfull. Had a 54 lincoln OHV v-8 that book said to idle at 450-500 rpm- loved to just watch it tick over. you could see the individual fan blades at idle. course it probally had a 75 lb flywheel.