Once again, I really advise you to consider electronic CDI ignition, especially for what you want to do. There are SO many advantages, including lighter weight which is always an important consideration on any warbird, but even more so with a twin.

Also, you don't have to move the crank keyway. The key is only there to guide the assembler in getting the timing set without checking it. The key does not hold the flywheel once it is tightened down, and can actually be left out. Leave the key out and set the flywheel anywhere you want. If it will make you feel better, you can add a drop of Loctite to the crank taper, but it's not necessary.

Have a look here:

http://www.rcextremepower.net/rcxpignitions.html

www.ch-ignitions.com

AV8TOR