HEI conversion benefits

yes if you can find one they come in at a mid price
but as with rubber products NOS is not necessarily best

the first versions from the mid 70s used electronics that needed to be protected with a perfectly matched condenser/capacitor or as Lucas did in the AB14 (Jaguar HEI ignition) used a clamping diode to hold any back emf on the primary to 300V.

modern ones if good quality do not need capacitor or diode protection

delco branded stuff is usually good.

dave