That is a very good timing link. It says it all.
My mild performer cam likes 14 and 21 at 3000rpm from the manifold. The Vacuum advance is adjusted for 8-10 more at whatever inches of vacuum the turns are set.
For slow/hard cranking .Check the wires to the starter if there is only one small gauge from the battery. Wrap 2 same gauge wires to the starter together. It puts the circut in parallel . Doubles the amps to starter but keeps the voltage the same.
Like 2 sets of jumper cables on a dead battery.