Although I have no idea why, the Holley Sniper Electronic Fuel Injection conversion seems to be popular, for a bottom of the barrel system. This is Holley's entry level system, and it shows it.
That said, the ignition conversions for them to use a direct feedback ignition into the EFI computer are unlike any other EFI ignition system in both components, and set-up/phasing.
The basic Sniper EFI direct input ignition system is one that uses a distributor that is derived from the original GM points system, and uses a single magnetic pickup, locked out mechanical advance, deleted vacuum advance, and an adjustable phase rotor.
These specialty MSD/Holley Sniper distributors do not cover all engines, only ones MSD has previously designed to use the adjustable rotor and GM points type top and cap. MSD reportss they have no plans to ad lines for other engines that did not use the GM top, nor other manufacture type distributors.
I have done a few different set rotor distributor conversions for the Sniper/FiTech systems, by setting both the rotor phase and degrees required for the electronic ignition curves as a part of the build process. These conversions use stock caps, rotors, and are drop-in, plug in, time, set the curves package in the EFI computer, go. One series of this non-GM top distributor I have converted, is for the International Harvestor V8 distributors, as a single example.
A note: Some few years ago, Mallory Ignition was sold to MSD, closing the Mallory facilities in Carson City, Nevada. MSD still carries a small inventory of Mallory items. MSD/Mallory was then purchased by Holley 4 years ago, to give Holley a company alignment that produces ignition systems for use in the different types of Holley EFI, and carburetted engine systems.