Not hard to do. Worked excellent. The MSD box was a nice improvement especially at idle. 18 intial worked great for my lil 408 and 35 total.

All you really do is get the initial what works best for your combo and you can do that in your driveway. And set the total at somewhere between 34-36 based on some engine info. You wekld up the slots and file them back to get the spread between initial and total ie 18 to 35 is 17 degrees spread. Weld up the slot and file back. see the notes for the sizing
The light springs let the advance come in quicker.