Robert,
Leave the decision til late in the build, new stuff comes out all the time and builds occasionally take a while to do, you dont want to fit outdated electronics.

Nick,
I had some done by spark erosion, at an engineers on our local industrial estate. Not vey expensive.
Pete.

Terry,
If your mags work ok off the engine then they are ok. There must be something wrong on the engine. At a guess it could be the earth return gone high resistance. Refit the mags and run a temporary wire from the mag case to the cylinder head near the plugs. This will eliminate any dodgy ...