We are aware of the fact that installing our HEI electronic distributors in 383 thru 440 Chrysler engines requires grinding of the cast iron cylinder head for distributor clearance. This is due to the fact that HEI distributors are larger in diameter because of the reliability & performance capabilities built into these distributors. The spark plug gap alone is increased from .035 to .055 so they have to be larger. The 65000 volt coil (stock is only 18000 when new) is built right into the cap of this unit, making it a bit taller too.
These are a true marine performance distributor. If you are not willing to take a rotary file and a drill motor to make this distributor fit, better stick with your old 1970s points distributor, but you’ll be doing it with great sacrifice over ours!