Right now I have a buddies truck in my shop, it is getting a 235 R&R. His is 12 volt, course mine is still 6 volt.
I will know for sure very soon. But I am inclined to believe the starting the engine ignition and starting motor is well served by a full 12 volts, more so if going to a HEI, which seems like a slam dunk if you are going 12 volt in the first place.

Steve


1953 Chevrolet 3100
261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done
In the DITY Gallery
Video of the 261 running

1964 GMC 1000
305 Big Block V6, sm420, the next cab off restoration