Not sure if you still need this info but just incase others read this later and want to find out.
The starter motor draws close to 100% of CCA rating that battery has at initial first turn of the starter motor and then sudden drop to between 200-400 amps usually depending a few things like starter condition, battery condition, temperature, voltage drop and if the engine has been started already.
just my 2c but hopefully it helps at least one person out haha
Dan