Battery/starter question

[chevyman0429]

So my chevelle has a bbc 427 in it. I bought the car with the motor already built so I really have no specifics on the intervals as far as compression ratio! The car started fine when I bought it. I had to replace the frame so I completely dismantled the car for some reason or the other I took the starter off. After I put it all back together it started like the starter needed to be shimmed but life got in the way and the car has sat for around 6 years. I did start the car every so often. I’m currently picking away at it and want to get this starter sorted out. Problem is now it turns over once or twice (sometimes a half turn) still sounding like it needs to be shimmed. So I put some shims in it got a bit better but still the same cranking problem. This morning I pulled out the spark plugs and it turns over great with a hair bit of starter grind but it does turn over quick! The battery I was using is a 600 cca battery could this battery be to small or is something else going on! I did pull the starter off and tried another I had laying around and the same problem! I did notice with both starters the starter gear remains touching the fly wheel just barely but we completely release itself if I tap the starter with the palm of my hand! Thanks