Parallel ignition systems, anybody tried running one?

Two comments.
- Use a GM HEI 4 pin module & E coil [ such as MSD #8207 ] & run 0.060" plug gaps.
That will do more than both of those systems. For even more 'oomph', use the MSD #83647 module or Summit copy.
- Using the Chrome box on the street will cook the coil from the increased current & dwell.