There's plenty of room on the firewall above the footbox to mount the MSD box without seeing it once the dash is installed.
Click Bonds are an aircraft grade system that allows you to bond studs, standoffs, cable tie mounts to a surface without having to drill any holes. They work great and I got mine at the Flight Shop.
http://www.theflightshop.com/ClickBo..._Bond_Info.php
Jason