before you go changing anything i would do a voltage drop test with a quality DVM. this will show you where the losses are and if that is the cause or part of the problem. is the starter pinion in proper mesh with the ring gear?
on start retards i learned the hard way that more retard isn't necessarily better (like i "thought" it would be). with a locked distributor and crank trigger you can back the timing up to the point where it starts firing the wrong cylinder...yea this causes problems.
as for spring tension remember that the lobe has two sides a noteworthy amount of that energy is returned when the valve is closing.
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I guess I could run 2 in series, if I needed to?
32 volts...GET ER DONE, i know you meant parallel 
