Last week I posted that I was jumping the starter directly to the new battery with jumper cables. The engine needed tested for coil operation and compression before I started work on it. (Been in storage for decades)( I was bypassing old old starter foot switch and cables ) I mentioned I had both wheels off the ground but was concerned about parasitic drive line drag as the engine was so slow to turn over.
Well there is nothing wrong with the drive train engine transmission drag. The problem jumping a battery directly to the starter with modern jumper cables was the cables were cheap 6 gauge wire just not enough to juice the starter. When I hooked 1/0 thick cables to the starter directly the engine just spun quickly as it should.