67-72 Drivers Side 340-360 Motor Mount Bracket Shim Question

Goin' 318 to 340. I understand the passenger side is cool. On the drivers side, how thick do the shims need to be, and am I moving the bracket and biscuit toward the firewall or toward the radiator? I assume I need 2 longer bolts to go through the 2 shims. Thanks guys, no cash for Schumacher so the shim route is for me. I'll use that $150 to upgrade the ignition.

My Barracuda thanks you for any info you can provide.