Mags produce a very weak spark at slow (cranking) rpm. If you're using
regular mags you might consider a SlickSTART before you start
re-plumbing your airplane:

http://www.unisonindustries.com/ourproducts/slickmagnetosandharnesses.html#slickstart

I bought one of these 5 or 6 years ago and have not had single failure
to start since installing it. My airplane now starts as reliably as my
Toyota. <g> The SlickSTART is only energised while the starter is
cranking so it has no affect on engine performance. It will fire the
plugs no matter what. Hot, cold, flooded, frosted, oil fouled,
whatever... your engine will start. I think I paid about $300 for it.
30 minutes to install.

--
Ron Laughlin
Legacy N44L (res)