This illustration shows the "three lobed stem" Motorcraft Y-block distributor you are looking for. Often available as a replacement for a 1964 Ford 292 truck application. Saves a hassle in explaining your intent to a sales clerk.
The point plate will look like this....
The points can be replaced with one of several aftermarket "points replacement" trigger units. The earliest version of the Pertronix Ignitior has a tendency to fry if you accidently leave it on with the engine dead - but any of the others will work fine. The upper rotor shaft (cam), points, and parts can also be swapped with the trigger unit of a Ford "Duraspark II" distributor (used from 1974 to 1985). This isn't a difficult mechanical conversion once you have the parts in front of you. The Ford triggers are pretty bulletproof - and parts are available. Once you have the Ford trigger in there - all sorts of control boxes and coils can be used to complete the ignition.
Basically the power of an inductive ignition spark has to do with how many amps you can reliably feed the coil to charge it. The higher energy electronic spark systems have coils with low primary OHMs - and therefore have to have higher rated grounding transistors and amperage control circuitry. If you are interested in doing your own - and for a low price and straight forward design - you cannot beat using the Ford trigger with a GM type HEI "four pin" controller.
None of this is rocket science and you will soon have a powerful ignition - with no great expense. Using the low OHM GM coil shown below will net "high performance" without the big price of big name hot rod parts suppliers. This one is out of a 4.3 S-10 pickup and had two nice snap connectors. Primary OHMs are about .5 - don't use one with a controller that doesn't have amperage control. Many of the "points replacement" unit specifically say they must be used with coils that don't have lower than 1.5 OHMs primary resistance - this would burn them up.
The GM 4 pin controllers are avaiable from several outfits - besides left over "real" GM parts. It gets mounted on a nice chunk of aluminum with heat couplant paste (and hidden away from water) to reject heat. Mounted outside the distributor (where it was originally located in the factory distributor) nets a huge gain in heat reduction.
I rig these up with an ignition ("on") operated relay to handle the amps needed to fully charge the coil - and do it out under the hood. Keeps the big loads out of your dash. The HEI controller uses a Motorola chip to turn on the coil with a transistor ground - and then shuts it off when it has handled all the heat it can reliably manage.
The above trace shows the results - the saturated coil has 5.5 AMPs of current and when the circuit breaks - the secondary will have a serious jolt to deliver.
Steve Metzger Tucson, Arizona