Here's the latest:

New rebuilt starter
New battery
Neg. battery jumped direct to starter case
Pos. battery jumped direct to starter motor terminal
+ 300 amp booster

Turns a little better but still too slow
Starter pinion gear still stays stuck in flywheel
No hint of firing

I pulled plugs from both rotors and it did turn faster but isn't that always going to be the case w/ no compression resistance?